For the filling, wash, quarter and finely dice the tomatoes. Dice mozzarella finely as well. Grate parmesan. Wash sage, shake dry and chop finely. Mix everything in a bowl. Season with salt and pepper.
Open the buns horizontally, but do not cut through. Spread the filling into the rolls. Bake the buns in portions in the sandwich maker. Meganice!.
What to do without a Sandwich Maker? Panini will be nice and crispy even with our 2-pan trick. For that, you'd better use a grill pan. This is heated without fat. Put 2 panini in the hot pan and fry them at medium heat for about 4 minutes.
Now please turn around! Then place a second pan on the panini and press down firmly. Attention: Be sure to use oven gloves or oven cloths - the pan is mega hot.