Place cornstarch, salt and pepper in a bowl. Toss chicken in mixture to coat.
Heat 1 T olive oil in a large skillet, over medium/high heat. Add coated chicken and brown both sides (about 5 -7 minutes). Remove chicken from pan and set aside on a plate.
Return skillet to stove. If pan is very dry, add 1 T olive oil. Add onion and peppers. Cook 3 minutes, stirring often and then add in the garlic. Cook 1 minute more. Stir in the white wine and lemon juice. Using a rubber spatula, scrape up the bits on the bottom of the pan (deglazing). Cook until wine is reduced by half. Add ¾ vegetable or chicken broth. Return chicken back to pan. Simmer 3-5 minutes. In a small bowl combine remaining 1 T cornstarch and 2 T broth and then stir into chicken mixture. Allow to simmer until chicken is cooked thru.
Add prepared pasta to pan, tossing well to coat. Stir in 1 T butter and parsley to finish.