Rub chicken breast with pesto and spread evenly. If time, place in a food storage bag and refrigerate to allow time for marinading prior to cooking.
Move chicken to a cutting board and dice. Using kitchen shears makes this step slightly quicker. Heat a large skillet to medium high heat.
Add chicken to the pan and cook until internal temperature reached 160 F. Remove chicken from pan and cover.
To the pan add diced zucchini. Sprinkle with salt and pepper. Sauté a couple minutes then add drained diced tomatoes and oregano. Add chicken back to the pan and heat 1-2 minutes. Serve.