Make the meatballs: Heat oven to 400 degrees F. Line a large rimmed baking sheet with foil; spray with cooking spray.

In a large bowl, combine ground beef, bread crumbs, 1 teaspoon ground ginger, pepper, salt, 3 green onions, 2 cloves garlic, egg and 1 tablespoon gochujang until well mixed. Roll into 1-inch balls; place 1 inch apart on prepared baking sheet.

Bake 20-25 minutes until meatballs are cooked through.

Meanwhile, make the sauce: In a medium saucepan over high heat, bring 1/4 teaspoon ground ginger, 4 cloves garlic, soy sauce, 1/2 cup water, brown sugar, 1 tablespoon gochujang, rice wine vinegar, vegetable oil and red pepper flakes to a boil. Whisk cornstarch and 1 tablespoon water together in a separate small bowl until well combined; stir into boiling sauce until just combined.

Reduce heat to medium; simmer and stir constantly 8-10 minutes until sauce is thickened. Remove from heat.

Add the meatballs to the sauce and gently stir to coat. Serve meatballs warm topped with remaining 1 green onion, sesame seeds and cooked rice, if desired.