Preheat the panini grill or grill pan.
In a separate bowl, mix yogurt, anchovies, dried tomatoes, capers and olives together.
Take 2 slices of bread and spread butter only on one side of each slice with unbuttered side, of the slice, facing you and start staking the ingredients.
First spread some yogurt sauce, then 2-3 slices of fresh or soft mozzarella.
Second, 2-3 slices of fresh tomatoes and sprinkle some salt, black pepper, 3-4 drops of balsamic vinegar and 3-4 drops of olive oil per sandwich.
Third, place fresh basil leaves and drizzle some yogurt sauce on top.
Top with the other slice of bread with the buttered side facing you.
Grill Panini until golden and crunchy on both sides.