Blanch the peas in boiling water for three minutes; drain and rinse in cold water.
Heat a four-quart pot over high heat. Add the remaining 3 tablespoons of oil, garlic, and spring onions and mix well. Add the peas and other vegetables except the tomatoes and continue cooking over very high heat until the vegetables are tender. Add the tomatoes and season with salt and pepper. Remove the pot from the heat.
Cook the pasta according to package directions; drain. Toss the pasta with the vegetables over low heat, mixing in half of the herb pesto mixture. Serve with a dollop of pesto and garnish with Parmesan cheese and sprigs of cilantro.