Heat oil then saute sliced or diced onion with salt until it gets a translucent / glassy look, for 2-3 minutes.
Add pepper and saute them for another 2-3 minutes.
Add the tomato puree and paprika then bring it to boil.
Meatballs
Meanwhile mix raw, rinsed rice, salt, onion and meat.
Form balls of desired size. Optionally, fill some peppers with the meat.
Immerse the balls and / or the stuffed pepper into the simmering tomato sauce.
In case the meatballs aren’t covered fully, add more tomato sauce or fill it up with water. Add water sparingly as it will dilute the sauce and it needs to be cooked away at the end or thickened with some kind of starch.
Put the lid on then bring it to boil and keep simmering on low heat until the rice is cooked, for about 20 minutes. When the rice is done, the meat is done too and the balls are ready to be taken out.
Blend the remaining tomato sauce with the onion and the pepper. Simmer the tomato sauce further until it gets a desired thickness. Mind that it is a tad bit thinner when hot and it will thicken a bit when cooled to serving temperature.