Place meat into a bowl and add sake. Toss gently, set aside.
Make the spicy sauce. Add everything except for sesame seeds, onion, spring onion and peppers and vegetable oil. Mix well. Can add more gochujang if desired.
Add the spicy sauce to the meat and mix well using hands. Let it sit for 15 min.
Chop vegetables.
Heat a large surface non-stick pan and add oil. Cook the meat on high for 4-5 min or until meat is no longer pink. Add the vegetables and cook additional minute.