Bring a large pot of heavily salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Reserve 1 cup of pasta water before draining.

While pasta cooks, heat olive oil in a large skillet or Dutch oven over medium heat. Add diced onion and cook until softened, about 3-4 minutes.

Add minced garlic and cook for another minute until fragrant, being careful not to burn.

Add the trimmed asparagus pieces and cherry tomatoes to the skillet. Sauté for 5-7 minutes, stirring occasionally, until asparagus is tender-crisp and tomatoes just begin to soften.

Stir in the thawed peas, vegetable broth (or 1/2 cup reserved pasta water), and fresh lemon juice. Bring to a gentle simmer.

Drain the cooked pasta and add it directly to the skillet with the vegetables. Add chopped fresh parsley and basil, salt, black pepper, and red pepper flakes (if using).

Toss everything together thoroughly until the pasta is well coated. If the sauce seems too dry, add a splash more reserved pasta water until desired consistency is reached. Stir in 1/2 cup grated Parmesan cheese.

Serve immediately, garnished with extra Parmesan cheese and a fresh lemon wedge if desired.