Preheat your oven to 375°F and line a small baking sheet with parchment paper.
In a medium mixing bowl, combine the lean ground beef, egg, almond flour, finely diced yellow onion, minced garlic, sea salt, black pepper, and dried oregano.
Gently mix the ingredients by hand until just combined, being careful not to overwork the meat.
Form the mixture into a compact loaf shape on the prepared baking sheet.
In a small bowl, whisk together the sugar-free ketchup, yellow mustard, and apple cider vinegar to create the glaze.
Brush the glaze evenly over the top and sides of the meatloaf loaf.
Bake for 25 to 30 minutes, or until the internal temperature reaches 160°F.
While the meatloaf rests for 5 minutes, steam the green beans until they are tender-crisp and vibrant green.
Slice the meatloaf and serve immediately alongside the steamed green beans.