In a heated skillet add some cooking oil and cook the sausage on medium high heat. Stir until the sausage is half cooked (for 1 to 3 mins depending on the sausage).
Add the bell peppers and onions. Stir and cook until they are wilted (for 1 to 2 mins).
Reduce the heat to medium heat. Pour in the sauce and mix with the rest of the ingredients (for about 1 min). Remove the skillet from the heat. Serve it with steamed rice and other Korean side dishes.