Preheat your oven to 375°F and line a rimmed baking sheet with parchment paper.
In a medium mixing bowl, combine the lean ground beef, egg, almond flour, finely diced yellow onion, minced garlic, tomato paste, sea salt, and black pepper.
Gently mix the ingredients by hand until just incorporated, being careful not to overwork the meat to ensure a tender texture.
Shape the mixture into a compact rectangular loaf and place it on one side of the prepared baking sheet.
Place the halved baby potatoes on the other side of the baking sheet in a single layer, ensuring they have space to roast.
Bake for 25 to 30 minutes, or until the internal temperature of the meatloaf reaches 160°F and the potatoes are fork-tender.
While the meatloaf and potatoes cook, whisk together the Greek yogurt, chopped fresh dill, and lemon juice in a small bowl to create the sauce.
Once the potatoes are finished, remove them from the oven and immediately toss them in the creamy dill sauce until thoroughly coated.
Allow the meatloaf to rest for 5 minutes before slicing and serving alongside the warm, creamy potatoes.