In large skillet over medium heat add oil and garlic, cook 2-5 min. Don't burn garlic. Add sweet potato, red bell pepper, tomatoes, and water. Cook, stirring occasionally, until pepper is crisp-tender. Remove from heat, cover, keep warm.
Drain pasta, reserve 1/2 cup cooking water. Return pasta to pot. Add veggie mix, remaining oil, parsley, tarragon, lemon juice, salt and cheese. Toss to combine. Add the reserved water 2 Tbsp. at a time to desired consistency.