Place a large skillet over medium heat with 3 tablespoons sesame oil. On a cutting board, remove any fat and/or silver skin from the pork with a small, sharp knife. In a medium bowl, mix the sliced pork and cornstarch together. Once skillet is hot, add the pork and stir fry both sides until it becomes crispy, about 5 minutes. Pour in the Gochujang sauce and combine thoroughly with the pork, cooking for another 5 minutes over low heat. Remove from heat and place pork in a clean, covered bowl.
Put remaining tablespoon of sesame oil back in the skillet over medium heat. Stir in the green onions and garlic and cook 2 minutes or until garlic is lightly brown. Add ginger, corn, red and green peppers to the pan and sprinkle salt and pepper over top. Stir frequently until peppers are slightly soft and corn has turned golden, about 5-7 minutes. Put pork back into the skillet, thoroughly mixing it all together in the pan for 1-2 minutes over low heat. Remove from heat. To serve, divide the rice among bowls and top with pork and vegetables, sprinkling sesame seeds over top of each bowl.