Cut leftover roti into slightly bigger size pieces.
Now, in a mortal pestle, add garlic cloves and red chili powder. Crushed it.
Then heat oil in a pan, add mustard seeds, cumin seeds, a pinch of hing, and curry leaves. Sauté for a minute.
Add garlic paste and sauté till oil separates from its sides.
Add turmeric powder, red chili powder, coriander powder, garam masala, and salt to the buttermilk. Mix well.
Add buttermilk and water into the pan. Stir continuously and bring it to a boil.
Then add roti pieces and mix well.
Cover and cook for 2-3 minutes on medium flame. So roti becomes soft and absorbs the flavor of all masala.
Garnish with coriander leaves and serve vaghareli rotli with onion slices.