Cut open one end of the wax gourds and scoop out the seeds.
Reserve the cut off pieces.
Heat the oil in a pan and saute the onions till golden brown.
Add the ginger and garlic pastes and the chopped tomatoes.
Stir for a minute or two and add the curry powder, sugar and salt to taste.
Cook till the tomatoes are thick and pulpy.
Add the mashed potatoes to half the tomato mixture and sprinkle in the garam masala powder.
Fill the wax gourds with the potato-tomato mixture along with a few raisins.
Cover the wax gourd with the cut-off end and secure with toothpicks.
Place half the reserved tomato sauce in a deep pan and arrange the wax gourds in it.
Cover with the remaining sauce and cook for 20 minutes or until wax gourds are done, shaking the pan gently from time to time.
Carefully remove the toothpicks and serve hot.