In a large skillet heat oil over medium heat until hot but not smoking. Add cumin seeds until they begin to pop.
Add onion and cook until softened, about 2 minutes. Stir in jalapeno pepper and seasonings.
Cook a further 3 minutes. Stir in potatoes and chickpeas and coat with spices. Pour in water and cover pan.
Reduce heat to medium low and cook for 15-20 minutes until potatoes are tender.
Sprinkle with cilantro and green onion. Spoon into warmed roti skins or whole wheat flour tortillas, fold in side flaps and roll up like an envelope.
