What is Pesto?

Pesto* is a cold-prep green sauce made with herbs and alliums suspended in oil. Most pestos call for some form of nut or cheese. In the general sense, chefs may specify “loose pesto” when there are neither cheese nor nuts in the sauce, or when the sauce has an abundance of oil. In general, pesto is made from herbs in the mint family, almost always from basil. The * distinguishes a generalization to the traditional meaning of the word.

Classification

Basil pesto is the common pesto. Its recipe typically calls for five key ingredients: $$ \begin{aligned} \textrm{basil pesto} = \textrm{basil} &+ \textrm{extra virgin olive oil} + \textrm{garlic} \\ &+ \textrm{parmesan cheese} + \textrm{pine nuts} \end{aligned} $$

Chimichurri includes a vinegar, usually red wine vinegar, which pesto does not, although pesto can suspend acid through citrus. Chimichurri often uses rough chopped or ground herbs, almost always oregano and parsley, but some modern applications will puree chimichurri as one does with pesto.¹

Pesto is also different from gremolata, which like chimi is also made with parsley, so you may refer to carrot-family herb sauces as either gremolatas or chimis, and mint-family herb sauces as pestos, and chefs will know what you mean, even if they don’t quite agree with the abstractions.

A table is provided as a summary of these three sauce’s distinctions.

	Pesto	Gremolata	Chimichurri	Spring Sauce
Herb*	Basil	Parsley	Parsley + Oregano	Mint + Peas
Oil	Extra Virgin	Extra Virgin	Extra Virgin	Walnut Oil
Allium	Garlic	Garlic	Garlic	Green Onion
Nut	Pine nut	-	-	Pistachio
Acid	-	Citrus	Red Wine Vinegar	Pomelo
Wow	Parmesan	n/a	Chili Flakes	Chevre

“Green Sauces. The author made spring sauce up, but it’s very good on crostini.”

But there is a small catch, because some chefs may also say ‘arugula pesto,’ which might have no mint-family herb mixed in. This leafy sauce resembles pesto in process and appearence, and provides the effect of coating pastas in bright green colors, especially when suspended in stablized fat like reduced cream or mayonaisse. A chef can employ arugula for its liquorice and peppercorn aspects, or baby spinach which adds tang (like nori) when cooked, but she will most likely apply it because of its food coloring properties (vibrancy). Similarly, ‘spring pea pesto’ is made with a puree of spring peas and mint, and on crostini is a fantastic crudité.

In this way, pesto* is generalized from its elements, describing a sauce of process and appearence while flexible in its flavor balancing rules. This is pesto* as a category, not pesto as a set. For all intents and purposes, chimis and gremolatas are pestos*.

Ingredients

The key to most pestos is to use a motor driven device for pureeing the sauce. The two best tools available and in common use both in commericial and residential kitchens are the vitamix or immersion blender. Food processors and ninjas work just as well.

Hint: always add cheese last

Puree everything besides cheese first. You don’t want to gum up your blender, so you can fold the proto-pesto with grated parmesan in a mixing bowl after pureeing the produce. In restaurants, you can make a really fine proto-pesto (i.e., loose pesto) by pureeing the produce and oil for an extended period of time. It is easier on the motor and on the blades. You can be lazier picking your leaves on your basil or include more stems, because the cheese absent creates less friction. Save the cheese for last.

Greens

Most herbs from either the carrot- or mint-families will work great, and many green tops of root vegetables (turnip, radish) are, while not interchangeable, usable and often complimentary in pestos. Caution: while tarragon can be made into a pesto*, its deployment in cold-prep sauces is rare (marinades, green goddess dressing) and is typically utilized better in hot-prep sauces–especially béarnaise. Sage, rosemary, and lemon verbena require special practice. Thyme is time. Use edible garnishes. Keep away from the ornamental “perfumes”.

Recommend: basil, mint, parsley, oregano, marjoram, arugula
Avoid: lavendar, tarragon, lemon verbena, rosemary

Cheese

Try to stick with a hard cheese that has longer room temperature stability. Cheeses with hard interiors and developed rinds will impart the necessary fats and impactful aromas while also being more conservative in the funky bleu cheeses, chalky goat cheeses, or sour yet creamy compositions of farmer/cottage style cheeses–namely, ricotta, cotija or paneer. An old queso fresco that has been air dried in the fridge, however, is a mighty substitute to parmesan on a budget.

Recommend: parmesan, hard rind, feta, crumbly
Avoid: soft, bleu

Citrus?

Of course, pesto is also seasoned (sodiums, peppercorn) and lemon zest or lemon juice is an especially common addition. Adding citrus tunes flavor, because it combats salinity (parmesan saltiness is not equal between products) and piquancy (garlic cloves grown in drought can be remarkably ‘hot’). Because lemons are a hybrid of pomelo and citron, grapefruit juice is an equally applicable substitute.

Recommend: lemon zest, grapefruit juice, kombucha vinegars
Avoid: orange, distilled vinegars

Nuts

Pine nuts are the nut of choice in recipes from canonical sources. People don’t have pine nuts in their house. They do have other nuts leftover from baked good preperations. In restaurants, pine nuts are toasted in hot ovens. They are applied whole to pizzas and salads, so because they can live in a recipe and two auxillary dishes, they define themselves as roleplayers in menus and inventories. However, pine nuts are expensive. Because they are normally toasted, errant chefs may leave them in ovens for moments too long, destroying a product whose cost is equivalent to whole numbers of the average hourly wages. This is not good for anyone. I’ve never done this before, I swear.

Instead, some nontropical tree nuts are immediate substitutes if you are concerned only with the context of pesto: walnut, almond, and pistachio. This does not mean cashews are off limits, nor peanuts. Consider the role they play with basil and different oils in Thai cuisine. But maybe we don’t often think of peanut butter and parmesan together, so we avoid peanuts in pesto. That doesn’t mean you are violating international treaties by substituting deluxed mixed nuts from the grocery store in place of pine nuts. Pine nuts are the most replaceable element of classical pesto.

Recommend: pine nut, walnut, almond, pistachio
Avoid: peanut, cashew, macadamia, brazil, pecan

Oils

It is by no coincidence that extra virgin olive oil is the go to substrate (notice also olives and the alternative nuts previously mentioned grow adjacent to each other). Its Mediterranean origin is the required consideration for almost all member dishes in its cuisine. Some oils are better than others when olive oil is out: avocado, walnut, grapeseed. Avoid soy and canola oils which are better suited for frying, and harm basil less in lite applications like salad (Italian) dressing. Coconut oil can be used, but is not ideal because of its high melting point. However, you can create a spreadable pesto by using coconut oil–if the proto-pesto wets are tempered into coconut oil carefully. Coarser nuts in the spread make for a provocative but health-conscious party favor.

Recommend: extra virgin, walnut, avocado
Avoid: canola, soy, peanut

Alliums

Lastly, we generalized garlic to alliums above for good reason. You can make garlic scape pesto, which uses the green tops grown above earth from the garlic bulb. But, you can also use spring onions and/or shallot bulbs in place of garlic, which is especially more pleasant with lakefish and seafood. Although, garlic is preferable to onion in the regime of shellfish and, notably, the mollusk. You can also use radish bulbs, as well as radish or mustard greens in pesto, which simulates “bite”. In place of garlic, this is a quite useful substitution when pestos are applied in dressings for leafy salads or pasta salads.

Recommend: fresh garlic, young onions, shallot, some pickled
Avoid: large onions, leek, pearl onion, cooked garlic

Recipe

I’ve included a basic production recipe for Basil Pesto that creates a structurally “loose” pesto. My application could be added to heavy mayo for basil aioli, brushed on bread for grilling, and thickened with reduced (50%) cream for penne pasta dishes (bechamel cheese sauces work there, too). Cheese plays a more vital role when pesto is a topping where the goal is to gratinize, or in the presence of crackers.

What is sauce?

When you play this game of generalizing sauces into irreducible primitives, you eventually question with good reason why the five mother sauces are the way that they are.

If postulated today, there would no doubt be endless criticism of its organization, lack of other fundamentally different sauces (gastriques?), exclusion of other world foods, and few would be convinced of any universality. But Escoffier’s postulate has historical importance defining the role of these hot-held sauces in a greater culinary scope. Less valuable now as theory, it is more so enforced as a performance lesson: a chef must learn how to make the mother sauces to be the best in her trade.

If you were to reduce every cold sauce into fundamentals (vinaigrette, aioli, coulis, etc), to what extent can you? There is at least some argmunent: the preperation does require special work. While the heated sauces have an additional thermal parameter (‘careful not to scald, to break..’), the cold sauces spend energy kinetically: emulsify, puree, grind (‘careful not to overwhip, to break..’). In this sense, attention isn’t voluntary, so it separates itself from chopping, fermenting, or stirring to mix, giving an argument of practicality some teeth in the need for order. No, Ranch is not a mother cold sauce, but mayo does require special work and is an elemental part of Ranch.

In my mind, I do consider some categories of cold sauces as fundamental to the education of the garde (those mentioned, probably closer to seven in total). So with liberty, let’s for sake of argument hold salsas and pestos in different regard. I cannot speak to the genre it belongs, but: if you have never tried blending tomatillo and basil together, you are missing out on one of life’s best kept secrets.