Preparing batata vada for vada pav,
Boil 2 large potatoes, about 350 grams till they are completely cooked. Peel and then mash them with a fork in a bowl.
Heat 2 to 3 tsp oil in a small pan. Add 1/2 tsp mustard seeds and crackle them. Then add 7 to 8 curry leaves and asafoetida. Stir and saute for about 5 seconds.

Then add 6 to 7 garlic and 1 to 2 green chilies, which have been crushed in a mortar pestle. add 1/8 tsp turmeric powder. stir till the raw aroma of garlic goes away. pour this tempering in the mashed potatoes, add 1 to 2 tbsp chopped coriander leaves. also add salt.

Mix everything well and then make small to medium balls from the mashed potato mixture. flatten these balls a bit. cover and keep aside. In another bowl, make a smooth batter from 1 to 1.25 cups besan/gram flour, 1/8 tsp turmeric powder, a pinch of asafoetida, a pinch of baking soda (optional), salt and 1/2 cup water.

The batter should not be too thick or thin. if the batter becomes thin, add 1 or 2 tbsp of gram flour. if the batter becomes thick, then add 1 or 2 tbsp water. keep aside,frying batata vadI in a kadhai or pan, heat oil for deep frying.

Dip the slightly flattened potato balls in the batter and coat it evenly with the batter.
gently drop these batter coated potato balls in medium hot oil.
depending on the size of the kadai or pan, you can add more or less of the vadas while frying.
deep fry these batata vadas till golden evenly.
drain them on kitchen paper towels. make all batata vadas this way and keep aside.

When they are still hot or warm, you need to serve them. take all the chutneys and pav on your work surface and assemble the vada pav, Slice the pav without breaking it into two parts and keep aside. If you don't have sweet chutney, then just make the vada pav with green chutney.

Spread both the green chutney and sweet chutney on the sliced pav. You can also spread green chutney on one side and sweet chutney on the other side. Sprinkle the dry garlic chutney. this is optional and if you don't have you can skip it.

Place the hot batata vada sandwiched in the bread slices.
Serve vada pav immediately or else the pav becomes soggy. You can also serve some fried green chillies and both the chutney along with it.