I often like to joke if it’s green, it can be turned into pesto; but that’s not too far off.
Pesto is derived from the Italian word pestare, meaning to pound, and it refers to the traditional method of preparation with a marble mortar and a wooden pestle. When we think of pesto, visions of the classic Italian sauce come to mind, but myriad versions of this “pounded sauce” exist. Some stay true to the original Genovese recipe of garlic, pine nuts, basil, Parmigiano-Reggiano, and olive oil, while others are inspired by those ingredients but have a character all their own. These days, pesto has become a generic term for any kind of sauce that’s been pounded (or processed) into a thick, green condiment.
You can make pesto with many other herbs besides basil, as well as other leafy greens. You can substitute crumbly Cotija for grated Parmesan or pumpkin seeds for pine nuts. You can omit the cheese entirely or add other spices to give it more heat. And you can make the pesto as thin or as thick as you like, to use as a sauce for pasta and pizzas or a spread for sandwiches and crostini. (Get the recipe for Linda's chunky here.)
I always keep a jar of pesto in the fridge for its versatility; it can elevate the blandest of dishes into the most flavorful of concoctions. To perk up a pot of minestrone, stir in a few spoonfuls of pesto. If you want to add a little special something to chicken, steak, potatoes, or carrots, pesto makes an easy and elegant sauce for drizzling.
Two summer heros come together in this basil and tomato leaf pesto Source: The No-Waste Vegetable Cookbook / Harvard Common Press
Preparing your own pesto out of the odds and ends from your pantry and produce bin is simple once you know the formula. The proportion of greens can vary by up to a cup, give or take, as it depends on whether you use the tender leaves of vegetables or their denser stems and stalks. Stronger-flavoured herbs, like sage and tarragon, should be paired with milder tasting herbs like parsley and basil. Stems from a few different greens can be tossed in together, so save your stems throughout the week and turn them into an “anything goes” stem pesto. I often add a small handful of herbs or greens (like coriander or spinach) to my stem pesto for a smoother texture. (Get Linda's kale stem pesto recipe - it's also great for cauliflower or broccoli stems).
Pair kale stems with basil and walnuts in this fresh and earthy pesto Source: Will Taylor / Harvard Common Press
A foolproof formula for pesto
Makes 1 cup
2 cups (weight will vary) packed herbs or greens
½ cup (weight will vary) grated hard cheese
1⁄3 cup (weight will vary) toasted nuts or seeds
3 garlic cloves
¼ to ½ cup (60 to 125 ml) oil
Salt to taste
Herbs or greens: The flowers and leaves of basil, parsley, coriander, mint, sage, thyme, tarragon and nasturtiums; the fronds and flowers of dill and fennel; rosemary, oregano and marjoram flowers; chive blossoms; garlic chives; scallions; green garlic shoots; garlic scapes; dandelions; rocket; spinach; watercress; mache; carrot greens; kale and/or kale stems; silverbeet and/or silverbeet stems; broccoli and cauliflower stems; shelled peas and/or pea shoots; shelled faba beans and/or faba leaves; bean leaves;
Cheeses: Parmesan, pecorino, grana Padano, asiago, cotija (for a vegan pesto made without cheese, try Linda's , or see for a pesto using nutritional yeast)
Nuts or seeds: Pine nuts, walnuts, peanuts, pecans, almonds, pistachios, cashews, macadamias, hazelnuts, sunflower seeds, pumpkin seeds, sesame seeds, hemp seeds.
Method and storage
Pesto is typically made one of three ways. The traditional method comes from its namesake and involves pounding the ingredients together with a mortar and pestle. Purists may insist this is the only way to properly release and blend all the flavours and oils, and to a certain extent, this is true. But in a modern kitchen, a food processor or blender does the job quite well, and it’s my go-to method. (Get the recipe for Linda's fennel frond and ginger pesto .)
On most modern food processors, the plunger that fits inside the feeding tube has a tiny hole at the bottom, and it actually serves a purpose. Pour your oil into the plunger and let it slowly stream into the bowl while the processor is running. It saves you the work of drizzling in the oil yourself.
Linda Ly's fennel frond and ginger pesto Source: Will Taylor / Harvard Common Press
You can also mince and combine all the ingredients with a knife or mezzaluna, adding a drizzle of olive oil, in the end, to hold the sauce together.
If you don’t use all the pesto right away, pack it tightly into an airtight jar and pour a thin layer of olive oil on top before refrigerating. The oil will help prevent the pesto from oxidising and turning brown (though it’s still perfectly edible when it’s discoloured).
Three easy ways to freeze pesto
You can also freeze the pesto for future use, especially when you’re craving a fresh burst of summer flavour in the dreary winter months.
1 Pour the pesto into a resealable plastic bag, flatten it out, and freeze. If you’re making large batches of pesto, you can stack individual bags of one-cup (235 ml) servings on top of each other.
2 Use a small cookie scoop or a wide spoon to scoop single portions of pesto onto a parchment-lined baking sheet. Place the baking sheet in the freezer for several hours until the pesto balls are firm. Store them all in a freezeproof container and thaw only what you need each time.
3 Pour the pesto into an ice cube tray and freeze. Each mould is usually a 3 tsp (15 ml) worth, and you can pop out a pesto cube anytime you need one.
Pesto vinaigrette
For a quick and simple salad dressing, start with a smooth, thin pesto (or add more oil as needed to make it pourable). Whisk together ¼ cup (60 ml) pesto and 1½ tablespoons (30 ml) wine vinegar, taste, and add more vinegar if desired.
Make it your own
Growing up in an Asian household most of my meals were vegetable-centric, due in part to a sense of thrift and the food culture in my family's homeland, Vietnam. I was taught that all parts of the plant were one and the same - that the roots, stems, leaves, flowers and seeds were equally precious. ... I intend to show you the boundless possibilities of produce - applying the nose-to-tail approach to vegetables in what I like to call top-to-tail (or seed-to-root?) cooking.
Food should always be fun, and I encourage you to experiment with recipes and make them your own.
This is an edited extract from by Linda Ly, photography by Will Taylor (Harvard Common Press, $35). Linda Ly is the keen gardener and cook behind the blog. 
Source: Harvard Common Press
