Peel and finely chop the onion. Chop chicken into small pieces. Heat 3-4 tablespoons of olive oil and sauté the onions and chicken over medium to high heat. Add salt and stir continuously until the chicken pieces are sautéed on all sides. Finely chop the tomato and allow to drain in a colander for a while. In a bowl, mix the yogurt with the eggs. Add the cheeses, parsley, tomatoes and sautéed chicken, add a little freshly ground pepper and stir. Following the instructions, make the rolls. Place the rolls on a shallow baking tin. Beat the egg with 1 tablespoon of water, brush the surface of the rolls and sprinkle with sesame seeds. Bake in a preheated oven at 200°C for 30 minutes.
Serve warm.

For making Mini Fillo Pastry Rolls:
Cut the pastry sheets lengthwise in halves. Cut each half into 3 pieces. Brush 3 sheets with olive oil and stick them together. Take a spoonful of the filling and place it near the edge of the shortest side. Fold the long edges of the pastry sheet over the filling. Roll up the sheet. Brush the edge of the sheet with some butter to stick. Continue in the same way to make all the rolls.