In a food processor, combine pineapple, garlic, and ginger and pulse until smooth. Then stir together with soy sauce, brown sugar, sesame oil, gochujang, pepper, and 1 tablespoon sesame seeds.
Cube steaks into about 1-inch cubes and add to a bowl with marinade. Stir together well. Cover and let marinate for at least an hour, but not more than 3-4 hours.
Remove steak from marinade and skewer on soaked bamboo skewers alternating with peppers and red onions.
Preheat grill to medium-high heat. Make sure grill is clean. Right before grilling, rub grill with canola oil.
Grill kabobs for 3-4 minutes per side, turning and grilling on all sides so the steak is cooked through medium-rare and the veggies are charred in spots.
Remove skewers and garnish with sesame seeds.
You can eat the skewers as is or serve on flatbreads with yogurt.