Step 1

Add the herbs, spinach or arugula, Parmigiano-Reggiano, nuts, garlic, lemon zest and lemon juice to a food processor and pulse a few times to roughly chop.

Step 2

Add in 4 tablespoons of the oil and blend until smooth, adding more oil if needed to reach a saucy consistency. Season to taste with salt and pepper.

Step 3

Transfer the pesto to a resealable container or jar, cover with a thin layer of olive oil and store in the fridge for up to 1 week or in the freezer for up to 3 months.