Preheat your oven to 375°F and line a small loaf pan or baking sheet with parchment paper.
Finely dice the yellow onion and green bell pepper, and mince the garlic clove.
In a large mixing bowl, combine the ground beef, egg, almond flour, diced onion, diced bell pepper, minced garlic, sea salt, black pepper, and dried oregano.
Gently mix the ingredients by hand until just incorporated, taking care not to over-compress the meat.
Shape the mixture into a uniform loaf and place it on the prepared baking sheet or into the loaf pan.
In a small ramekin, whisk together the tomato paste, maple syrup, and apple cider vinegar until smooth.
Spread the tomato mixture evenly over the top and sides of the meatloaf.
Bake for 35 to 40 minutes, or until the internal temperature reaches 160°F and the glaze is bubbly.
Allow the meatloaf to rest for at least 5 minutes before slicing to ensure it remains moist and holds its shape.