Cook the tortellini: Bring a large pot of salted water to a gentle boil. Add tortellini and cook until just tender, usually 2–3 minutes for refrigerated or per package for frozen. Do not overcook.

Drain and cool slightly: Drain well, then spread the tortellini on a sheet pan for 3–5 minutes so steam escapes. Toss with 1 tablespoon olive oil to prevent sticking.

Prep the mix-ins: Halve the tomatoes, dice the cucumber, thinly slice the onion, and cut mozzarella if not using pearls. Roughly chop olives if using.

Lighten the pesto: In a large bowl, whisk pesto with a squeeze of lemon juice, 1 tablespoon olive oil, and a splash of pasta cooking water (or plain water) to create a looser, silky sauce.

Toss it together: Add the slightly warm tortellini to the bowl and coat with the pesto mixture. Fold in tomatoes, cucumber, onion, olives, and mozzarella. Add spinach or arugula last to keep it perky.

Season and brighten: Add lemon zest, a pinch of red pepper flakes, and black pepper. Salt to taste—remember pesto and cheese are already salty.

Finish and serve: Top with shaved Parmesan and toasted nuts for extra texture. Serve right away slightly warm, or chill for 30–60 minutes for a cool, cohesive salad.