Bau, or opo squash, (calabash, cucuzzi, bottle gourd, etc) is a long pale green squash that can be found at Asian markets. It has a flavor similar to cucumbers mixed with zucchini. My daughter and I love this squash raw to snack on. My sister in law introduced me to this simple soup. She pairs it with Thit Kho, stewed pork, or other Kho recipes. This soup pairs nicely with salty dishes to mellow out the flavors. Can serve over rice to make a light stew. I sometimes add 2 c fish stock and 4 c of water. Prep time varies on how long the squash and shrimp needs to cook. If using this soup as a side to Kho dishes, I use the smaller amount of shrimp. If serving alone over rice, I use more shrimp.