Mumbai potato fritter burger (Vada pav)

1. Boil the potatoes in their skins until tender, peel and mash coarsely. Pound the garlic and green chillies to a paste in a mortar.

2. Heat the tablespoon of oil in a frying pan, fry the mustard seeds, then add the asafoetida, curry leaves and garlic-chilli paste and fry for half a minute. Stir in the turmeric, potatoes and salt, mix well and let it cool a little.

3. Shape the mixture into 8 balls and flatten them slightly.

4. For the batter, whisk the gram flour with the turmeric, salt and enough water to make a thick batter that drips slowly off a spoon. Heat the oil in a smaller, deep pan.

5. Dip the balls in the batter so they are coated all over and fry 2-3 at a time, turning, for 3-4 minutes until golden brown. Lift onto kitchen paper.

6. Split the rolls, but not all the way through, spread with green and sweet chutney and put two hot vadas in each. Serve at once with a fried green chilli.

Tip: Mumbai's "burger", invented in the 1960s as a quick, cheap lunch for textile mill workers. The classic accompaniment is dry garlic chutney (lehsun chutney), sprinkled inside the roll.