Boil the pasta: Bring a large pot of salted water to a boil. Cook pasta until just al dente.
Reserve 1 cup of pasta water, then drain.
Sauté aromatics: While pasta cooks, heat olive oil in a large skillet over medium heat. Add onion and a pinch of salt; cook 3–4 minutes until softened. Stir in garlic and red pepper flakes; cook 30 seconds until fragrant.
Cook firm veggies first: Add broccoli and asparagus (or green beans).
Sauté 3–4 minutes, stirring occasionally, until bright green and slightly tender.
Add quick-cooking veggies: Stir in zucchini, yellow squash, and cherry tomatoes. Cook 3–4 minutes more until just tender but not mushy. Add peas and warm through for 1 minute.
Build the sauce: Pour in vegetable broth and plant milk.
Simmer 2 minutes. Stir in lemon zest, lemon juice, and nutritional yeast. Season with salt and pepper.
Toss with pasta: Add drained pasta to the skillet.
Toss well to coat, using splashes of reserved pasta water as needed to loosen and create a glossy, silky sauce.
Finish with herbs: Stir in fresh parsley or basil. Taste and adjust seasoning with more lemon, salt, or pepper. Add capers or vegan parmesan if using.
Serve: Plate immediately.
Garnish with extra herbs, a sprinkle of nutritional yeast or vegan parmesan, and toasted pine nuts if you like crunch.