Heat oil in a large nonstick skillet coated with cooking spray over medium-high heat.
Add chicken to pan, and cook 4 to 5 minutes on each side or until chicken is done.
Add tomatoes, bell pepper, 1/4 cup cilantro, 2 teaspoons hot sauce, and thyme to pan. Bring to a boil; cover, reduce heat, and simmer 5 minutes. Uncover and simmer 5 minutes.
Stir in remaining cilantro. If desired, serve with additional hot sauce and garnish with thyme sprigs.