Karela, bitter melon or balsam pear.

From Bladhom: More jagged and narrower than Chinese variety of bitter melon.  Brighter green and younger are better. Older, yellowish ones are tough with fibrous cores. When young, the whole gourd is eaten, including pith and seeds. In older ones, scrape out seeds.

Eaten raw, thinly sliced in salads or added to rich spicy curries to mellow bitterness.  Stir-fried w/spices and lime juice, deep-fried into crunchy chips. Bengalis - soup, punjabis slit and stuff with spicy mashed potatoes or ground almonds and pan-fry. Pickled w/garlic & tamarind. Salt or blanch to reduce bitterness. Small, firm, shiny. Avoid overripe, soft yellowish.