Wash, drain and cut chicken breast into cubes. Take olive oil and chicken cubes in a large pot. Cook until it absorbs all of its juice over medium heat, stirring occasionally. Cut off the top of chilli peppers and wash. Add chopped onion, and peppers into the pot and cook for 5 minutes. Add tomato paste to the pot and stir for 5 minutes. Chop mushroom into cubes. Add mushroom cubes into the pot and stir. Add black pepper, and salt to the pot, stir. Turn the heat down to low and simmer until mushrooms are soft.