If not already toasted, warm the pine nuts in a dry skillet over medium heat for 2-3 minutes, shaking often, until golden and fragrant. Let cool completely.

In a food processor, combine the drained roasted peppers, garlic, toasted pine nuts, grated cheese, basil, lemon juice, red pepper flakes (if using), salt, and black pepper. Pulse 8-10 times until roughly chopped.

With the processor running, slowly drizzle in the olive oil through the feed tube. Process until the pesto is mostly smooth with some texture remaining, about 30 seconds. Scrape down the sides once or twice.

Taste and adjust salt, lemon, or pepper as needed. For a looser pesto, add more olive oil 1 tablespoon at a time. For thicker, add more cheese. The pesto should coat a spoon but still pour easily.

Use immediately tossed with 1 pound hot pasta (reserve 0.5 cup pasta water to thin), spread on sandwiches, or dolloped over grilled vegetables. Or transfer to a jar, cover with a thin layer of olive oil, and refrigerate up to 5 days.