In a small skillet, add one tablespoon of the olive oil and heat for about 30 seconds. Add the finely chopped onion, garlic and dried chili flakes. Stir around and cook until the onions are softened and golden, about 5 minutes. Remove from heat and leave to cool.
In a small bowl, combine the milk with the bread crumbs. Stir to combine and set aside.
In a large bowl, combine the ground beef, bread crumb mixture, cooked onions, salt and pepper. Mix well with your hands.
Using a small ice cream scoop or a tablespoon, mound out portions of the meat mixture. Gently but firmly form into round balls. Don't overwork the meat or it will be dry. Repeat for all mixture and place on a plate.
Heat remaining olive oil in a deep sided medium sized skillet. Add the meatballs and cook for about 2 minutes until browned. Flip over and cook other side for about 2 minutes. Remove all meatballs from skillet and drain on paper towels.
Wipe the skillet clean of any remaining olive oil. Pour in the teriyaki sauce and set over low heat. Add the meatballs to the teriyaki sauce, cover and leave to finish cooking on low heat for about 12 - 15 minutes.
When cooked, remove from heat and garnish with sesame seeds. Serve with fluffy Basmati rice for a complete meal.