Adapted personally from YouTube channel 'Bokjumoni by Chef Lee Yeon-bok'.
Slice bell peppers and onions into strips.
Cut chili peppers diagonally.
Add cooking oil to a pan and sauté minced garlic.
Add sliced vegetables and chili peppers to the pan and stir-fry.
Add soy sauce, oyster sauce, and pepper, then stir while mixing well.