Prepare all the ingredients for the marinade in a small bowl.
200 gr tomato sauce, 200 ml vegetable broth, 60 ml liquid honey, 60 ml apple cider vinegar, 1 onion, 1 tbsp Dijon mustard, 3 tbsp brown sugar, 3 pinches of paprika, 1 garlic clove, 1 pinch of freshly ground black pepper