Mix together yeast, sugar, and 1/2 cup warm water in a bowl, then let stand until foamy, about 5-10 minutes.
Mix whole wheat flour and oats flour in another bowl and salt, olive oil and yeast mixture and knead with the help of warm water till soft and smooth dough. Keep the dough into greased container with some olive oil applied all over the dough and close the container.Rest for 2 hours or until it doubled in bulk (about 2 hours).
Punch down dough and cut into 8 pieces. Form each piece into a ball. Dust the working surface with flour and roll each ball into round like roti with rolling pin. Preheat oven/ electric tandoor (I used tadoor to make it) bake Pita bread till golden, about 2 minutes. Turn over with tongs and bake 1 minute more. Bake all pita bread in same way. Your pita bread is ready.
Mix boiled banana,salt, red chilli powder, onion, garam masala powder, chaat masala, coriander leaves, carrot and 4tablespoons oats in a bowl.
Divide mixture into 8 equal portions and shape into tikkis. Dip them in the milk and roll in oats and set aside. Heat a non-stick tawa and cook tikkis on medium heat, turning sides, till golden brown on both sides tikki is ready.
Cut pita bread from middle in half like packet and put tikki,onion,tomato, cucumber slice and lettuce leaf in the packet of pita bread and serve.
