Combine ground beef, ground pork, grated onion, egg, almond flour, salt, and pepper in a bowl. Mix gently until just combined.
Shape into 1 1/2-inch meatballs.
Heat oil in a large skillet over medium heat. Brown meatballs on all sides, about 6–8 minutes total. Remove and set aside.
Add broth to the skillet, scraping up any browned bits.
Return meatballs to the skillet, cover, and simmer 15–18 minutes until cooked through.
Remove meatballs. Temper sour cream with a ladle of hot liquid, then whisk it into the skillet.
Return meatballs to the sauce and warm through without boiling.
Top with fresh dill and serve.