This is how I make cholay :
Assuming you have the required quanitity of boiled cholas.
In a bartan , add a little water ( very little hardly 1/2 cup) with cholas and put of low flame. Add a tea spoon of NATIONAL CHANNA CHAT MASALA and mix , 1 tsp is never enuff so keep on adding more till you get the required taste and keep on mixing. Let it be on simmer for like 10 mins.
Cut boiled potatoes in cubes and slices of raw tomatoes. When you get the required taste in cholas add potatoes and tomatoes and mix well. Let be again on simmer for 10 mins.
I don't add any salt , lemon juice or imli water and yet the cholas turns out very yummy everytime. You can add more veges accordind to ur taste in it like onions , green onions , dhaniya etc.