Mondongo, or beef tripe , is a stew popular in Costa Rica, though it is not always available at the tourist prone restaurants. You should look to the more every day eateries and diners if you want to find this dish.
The base of the dish is tripe, which is the lining of a cow’s stomach. It's washed, prepared, cooked usually in a pressure cooker at high temperature, and either made into a stew (“sopa de mondongo”) or combined with a tomato sauce (“mondongo en salsa”) and vegetables. When properly cooked it should have no smell, and taste similar to a beef stew.
Most people would not readily think of consuming a cow's stomach, which is why this dish is sometimes hard to find in tourist restaurants. It's more a “working-class” dish, served in diners and bars. But despite all that, it's quite good. So if you're feeling adventurous, give it a try!