Calamondin

The Calamondin is a cross between a kumquat and a sour mandarin. They are extremely acidic, very juicy and contain a few seeds. Calamondin, which are very small in size, are rarely eaten and instead used as an ingredient where high acidity is desired. Calamondin halves or quarters may be squeezed into iced tea and onto seafood and meats. The juice is often used in preparation of gelatin salads or desserts like custard or chiffon pie. (from Melissa's/World Variety Produce)