Steps
1. Heat olive oil in a skillet over medium heat.
2. Add the sliced onion and cook slowly, stirring occasionally, until caramelized and golden brown (about 10 minutes).
3. Add the minced garlic and cook for 1 minute until fragrant.
4. Push onions and garlic to the side, season chicken breast with salt, pepper, and oregano, then add to the skillet.
5. Cook chicken for 5-6 minutes on each side until fully cooked and golden.
6. Add diced tomato to the skillet, stir, and cook for another 3-4 minutes until the tomato softens into a sauce.
7. Taste and adjust seasoning if needed.
8. Plate the chicken and spoon the onion-tomato sauce over it.
9. Garnish with fresh parsley if desired and serve hot.