In a bowl, mix the warm water with the paprika powder until smooth. Add the mustard, ketchup, and egg, stirring until creamy. Finely chop the fresh onion (or use roughly a cup of fried onion), then add to the mixture along with the minced meat, herbs, and breadcrumbs. Knead with your hands until everything is well combined, then season with salt and pepper to taste.
Shape the mixture into balls and place them on a baking sheet lined with baking paper. Bake at 200°C (392°F) for 20-30 minutes, depending on the size of the meatballs. The meatballs are done when golden brown and cooked through to an internal temperature of 74°C (165°F). They can be left to brown darkly for a crispier texture.