Cook pasta in water, reserving 3Tbsp cooking water, Place 1 cup Arugula. 1/2 C fresh parsley and basil, 1/4 C grated Parmesan, 1/2 tsp salt, 1/8 tsp red pepper flakes and 2Tbsp minced garlic in food processor; pulse until chopped. Add 1/4 C chopped walnuts. While processing, gradually add 1/3 C olive oil. Toss pasta with pesto, chopped plum tomato, and reserved pasta water.