Cut the chicken breast into pieces 1 cm thick and 5-6 cm long. Place in a bowl.
Sprinkle with 1/2 tsp red pepper, oregano, 1/2 tsp salt, finely chopped cilantro and finely chopped garlic, mix well, cover and refrigerate for 20-30 minutes.
In the meantime, chop the onion and cut the bell peppers into juliennes.
Pour 1 tbsp of oil into the pan and heat it well, sauté onions, bell peppers, 1 tsp red pepper and 1/2 teaspoon of salt, in about 4 minutes, (they should soften a little) take it out in a separate bowl.
Add 1 tbsp of oil to the pan and cook the marinated chicken fillet until no side is pink, add cooked veggies, pour lemon juice and mix well. Remove from the heat in a minute.Bon Appetit!