In a small bowl: combine/whisk all the sauce ingredients (soy sauce, mirin, sesame oil and sugar).
Heat the pan to medium-high.
Place ground beef/chuck in the pan and break into small pieces.
Cook for 3 minutes or until no longer pink.
Add minced garlic and cook for 1 minute or until fragrant.
Pour the sauce mixture into the pan and cook for 1-2 minutes or until the sauce has been absorbed.
Garnish with fresh chopped green onions and toasted sesame seeds.