Add the remaining tablespoon of oil to the same skillet. Add mushrooms, sweet pepper, carrot, and garlic; cook for 3-4 minutes. Add wine; simmer, uncovered, until liquid is reduced, about 5-6 minutes. Add tomatoes, onions, and oregano; stir to combine. Return chicken to skillet. Reduce heat to low and simmer, covered, for 15-20 minutes or until chicken is done (175º F). Note: If your chicken breasts are too thick it might need more cooking time.