Spray grill with any non stick spray or wipe grill liberally with oil to keep tuna from sticking. Grill tuna steaks about 1 minute per side. Tuna should be very rare still. (It should just be on grill long enough to get a touch of grill color.) Remove when marked.
Grill avocados until they have color then remove to cool. Dice up grilled tuna and avocado and place in a bowl. Add in all remaining ingredients. Toss gently to coat and refrigerate for at least 30 minutes to allow flavors to meld. Serve on a chip or crispy wonton wrapper.