Dice the onion and chop the garlic. Heat a little oil in a large pan over medium-high heat. Add the onion and garlic and fry for 2 minutes. Add the ground beef and cook for 3-4 minutes, stirring frequently, until browned. Season lightly with salt and pepper. Stir in the tomato paste and cook for 1-2 minutes. Deglaze the pan with a splash of water, scraping up any browned bits.
Transfer everything to a slightly larger saucepan. Add the kidney beans and canned tomatoes. If you prefer a thinner consistency, add a bit more water. Season well with salt, pepper, and paprika powder. Simmer over low heat for 10-15 minutes.
Top each serving with feta cheese. Serve with baguette on the side if desired.