Cook the pasta: Bring a large pot of salted water to a boil. Add pasta and cook until al dente according to package directions. You want it firm enough to hold up in the salad.

Cool the pasta: Drain and rinse briefly under cool water to stop the cooking. Shake off excess water. Toss with a drizzle of olive oil so it doesn’t stick.

Toast the nuts: In a dry skillet over medium heat, toast pine nuts or walnuts for 3–4 minutes, stirring often, until fragrant. Let cool.

Make the pesto: In a food processor, pulse basil, toasted nuts, garlic, Parmesan, salt, and pepper. With the motor running, stream in olive oil until smooth but still a little textured. Add lemon juice to taste. Adjust seasoning.

Prep the veggies: Halve the cherry tomatoes, dice the cucumber, and thinly slice the red onion. If using onion, soak it in cold water for 10 minutes, then drain—this keeps it from overpowering the salad.

Combine: In a large bowl, mix pasta with 3/4 of the pesto. Fold in tomatoes, cucumber, onion, mozzarella, and greens (if using). If it looks dry, add more pesto or a splash of olive oil.

Season: Add salt, black pepper, and a pinch of red pepper flakes if you like heat. Squeeze in a bit more lemon for brightness.

Chill (optional but recommended): Cover and refrigerate for 30–60 minutes to let the flavors mingle. Before serving, stir and adjust seasoning. Top with extra Parmesan and a few basil leaves.