Toss the asparagus in the garlic, lemon juice, and salt. Grill the asparagus until it just starts to develop a few blackened spots. The asparagus should still have some crispness to it. Cut the asparagus into 2-inch-long pieces. Bring the water to a boil. Boil the pasta until it is al dente. Toss the cooked pasta with the asparagus, parsley, and peas.