The acidity of the apple and the sour-sweet balsamic vinegar that perfectly balanced the (little) fat of the meat.
I cut the apple (Fuji) into rather thin slices, without removing the peel, and I divide each segment in half. To prevent the pieces of apple from darkening, we rub around a slice of lemon.
In each skewer, insert a piece of apple and a piece of meat cut into small cubes. I place the skewers in a greased baking dish with a little oil and lightly brush the surface of the skewers with a brush stroke of oil. I put the baking dish on the penultimate shelf of the oven, where I had lit the grill bringing it to 220 °; I then turn on the ventilation. After about a quarter of an hour, I turn the skewers over, add a little salt and continue to cook them for another 10-15 minutes.
Meanwhile, prepare the seasoning - in a small saucepan combine a tablespoon of lemon, 4-5 tablespoons of balsamic vinegar, a pinch of salt, a turn of pepper and a tablespoon of oil.
With a whisk we mix the ingredients well, then I put on the stove on low heat to make it thicken a little; then add a sprig of rosemary and continue to cook over a very low flame for a few minutes.
When the skewers are well cooked, I transfer them to the dishes and season them with a couple of tablespoons of balsamic sauce.