Preheat the oven to 375°F and lightly grease a baking sheet.
In a large bowl, combine the ground lamb, breadcrumbs, egg, 2 cloves of minced garlic, mint, parsley, oregano, feta, lemon zest, 1 tablespoon olive oil, salt, and pepper. Mix until just combined.
Divide the mixture into 8 equal portions and shape each into a small loaf. Place the loaves on the prepared baking sheet.
Bake for 22 to 25 minutes until the internal temperature reaches 160°F.
While the meatloaves bake, cook the couscous. Bring the water, remaining 1 tablespoon olive oil, and a pinch of salt to a boil in a medium pot. Stir in the couscous, cover, and remove from heat. Let it sit for 5 minutes, then fluff with a fork.
For the tzatziki, stir together the Greek yogurt, drained cucumber, dill, remaining 1 clove minced garlic, and lemon juice in a small bowl. Season with salt and pepper.
Serve the meatloaves over the couscous with tzatziki on the side.