Meanwhile, in a large skillet, heat 1 Tbsp oil & bell pepper over medium-high. Saute until peppers are tender. Add sweet potato, garlic powder, tomatoes & water. Cook 5-7 minutes, stirring occasionally. Remove from heat. Cover & keep warm.
Drain pasta, keeping 1/2 cup of pasta water & set aside. Return pasta to pot. Add vegetable mixture, remaining oil, parsley, tarragon, lemon juice & cheese. Mix well.
If needed, add pasta water gradually to reach ideal consistency. Serve immediatly.