Heat a medium skillet over medium heat, add vegetable oil in it. Cut the sausage lenghtwise and cut them into half moons. Chop onion and pepper and add them into the skillet with sausage. Cook them until onion is just golden. Peel and chop tomatoes and add them to the skillet, stirring occasionally, cook it until the juice of tomatoes comes up, approx. 10 minutes over medium heat. Add salt.