Preheat oven to 425°F/220°C.
In a large bowl, mix the pork, egg, onion, sesame seeds, garlic, ginger, salt, and pepper. Combine thoroughly.
Roll the mix into large balls, each about the same size as a golf ball.
Pour the cooking oil into a deep-sided roasting tray. Place the balls in the tray, making sure to leave space between each one so that they’re not touching.
Put the tray in the preheated oven and cook for 5 minutes.
While the meatballs are cooking, make the sauce. In a small bowl, combine the soy sauce, sesame oil, rice wine vinegar, mirin, and honey.
Take the meatball tray out of the oven. Pour the sauce mix over the meatballs, coating them as evenly and thickly as possible.
Put the tray back in the oven and cook for a further 15-20 minutes, until cooked thoroughly on the inside.
Remove from the oven and allow to cool for 5 minutes. Serve the meatballs over soba noodles. Garnish with chopped scallions and sesame seeds.