Grilled portobello mushroom and kasseri sandwiches

4 Rolls
4 Portobello mushrooms
4 Slices of kasseri cheese
1 Large onion sliced
1 Large red pepper
2 Tblspoon olive oil
3 Tblspoon balsamic vinegar
Freshly ground black pepper.

Clean and remove stems from mushrooms.
Grill mushrooms for a few minutes on each side.
Grill red pepper until skin is brown, remove skin and chop in thin slices add balsamic vinegar and pepper.
In a heavy frying pan add the 2 tblspoons of olive oil and sauté onion until transparent 2 to 3 minutes.

Assembly the sandwiches.
Warm up the rolls and cut in half.
Place one mushroom, some of the caramelized onion and red pepper and top with a generous slice of kasseri cheese.

The combination is mouth watering.