Arrange the biscuits on a plate. In a bowl, place potatoes, corn,onions, salt and chaat masala and mix. Divide into portions. Place aportion on each biscuit. Drizzle one-fourth teaspoon of red garlicchutney, half a teaspoon of green chutney and one teaspoon of sweettamarind chutney, one after the other, over each biscuit. Sprinkle rawmango on each biscuit and top it all with plenty of sev. Sprinkle apinch of red chili powder over each biscuit and serve immediately.