Preheat the oven to 375F. To a large baking dish add the potato pieces and smashed garlic cloves.
Make the Greek lemon suace by whisking together the lemon juice, olive oil, mustard, salt, pepper, dried oregano and garlic powder. Add half of the sauce to the baking dish, toss with the potatoes and then add 1/2 cup water to the baking dish too. Bake for 40 mins.
While the potatoes are baking, make the meatballs. Mix together all the meatball ingredients in a bowl and then once combined, scoop about 2 tbsp at a time and form into meatballs.
After 40 minutes, take the potatoes out of the oven and place the meatballs into the baking dish, nestled in between the potatoes. Drizzle the other half of the lemon sauce over the meatballs. Sprinkle the 1 cup of cubed feta throughout the baking dish. Bake for 18-20 more minutes or until the meatballs are cooked through to 165F.
Serve with fresh halved cherry tomatoes and fresh mint.