Prepare the vegetable Manchurian balls by mixing 1 cup finely chopped cabbage, 1/2 cup grated carrot, 1/4 cup finely chopped capsicum, 1/4 cup finely chopped onion, 2 tbsp cornflour, 2 tbsp maida (all-purpose flour), 1 tsp ginger-garlic paste, 1/2 tsp black pepper powder, and salt to taste. Mix well and form small balls.
Heat oil in a kadai or deep frying pan and deep fry the Manchurian balls until golden brown. Remove and place them on a paper towel to drain excess oil.
Prepare the rotis by mixing 2 cups of whole wheat flour, 1/2 tsp salt, and water as needed. Knead the dough and let it rest for 15 minutes. Divide the dough into equal portions and roll out each portion into a thin roti.
Heat a tawa or griddle and cook the rotis on both sides until they puff up and have light brown spots. Keep them warm by wrapping them in a cloth or foil.
Assemble the rolls by placing 2-3 Manchurian balls on each roti, along with sliced onions, chopped coriander leaves, and a drizzle of green chutney or tomato ketchup. Roll the roti tightly and wrap it in foil or parchment paper.