Ceviche with Ahi Tuna

This is a creation using both modern and traditional ceviche methods. The key of course is fresh fresh Ahi. One of the reasons that a really terrific ceviche is , well, really terrific is the type of fish and/or seafood used. It MUST be absolutely of the freshest quality. Some traditional recipes use ketchup which can be substituted for the tomato juice and Sugar.