In nonstick skillet, sauté chicken in oil over low heat until it turns white. Stir chicken constantly to keep it from sticking.
Add onion, garlic, green pepper, and tomato. Cook chicken mixture through. Remove skillet from stove and let mixture cool in refrigerator.
Meanwhile, place flour in large mixing bowl and stir in enough water to make stiff, tortilla-like dough.
When chicken mixture has cooled, mix in cheese.
Divide dough into 24 portions. With your hands, roll dough into balls and flatten each into 1/2–inch thick circle. Put spoonful of chicken mixture in middle of each circle of dough and bring edges to center. Flatten ball of dough again until it is 1/2–inch thick.
In very hot iron skillet, cook pupusas on each side until golden brown. Serve hot.
There are 303 calories in 1 serving of Pupusas Revueltas.