Wash the meat, dab dry and cut into cubes. Peel and slice the onion. Clean, wash and cut the bell peppers into pieces. Wash and clean the tomatoes. Put meat, onion, paprika and tomatoes on skewers. Mix 1 teaspoon of oil and lemon juice and brush the skewers with it. Season with salt, pepper and rosemary and leave to stand.
Peel and wash the potatoes and cut them in half lengthwise. Brush with remaining oil. Season with pepper and rosemary and place on the oven rack with the cut surface facing down. Grill under the preheated grill for about 20 minutes. Add the skewers after 10 minutes and grill with them. Arrange skewers and potatoes with the sauce. Garnish with tomato slices if desired