Preheat oven to 200°C. Roughly chop onions and put into a chopper with parsley sprigs and chop finely. Heat 1 tbsp oil in a non stick pan, arrange the bread slices in it and toast, turning sides till lightly browned. Place them on a plate.
Add the remaining oil to the same pan. Add onion-parsley and saute. When the onions soften and the raw smell disappears, add white sauce. Grate parmesan cheese directly into the pan.
Add salt, crushed peppercorns and mix well. (If you like it spicier, chop 1-2 green chillies and add to the onion mixture.) Spread this mixture generously on each bread slice.
Slice mozzarella cheese into thick squares and place over the onion mixture. Sprinkle red capsicum strips and grill the bread slices in the preheated oven till the cheese melts. Cut into triangles and serve immediately.