I made this the other day for some friends. I saw something similar on Iron Chef and I thought it was too easy not to try it at home. It's a nice and light appetizer and good for the summer.
1/2lb of sushi grade hamachi/yellow tail
great olive oil, salt and pepper
Thinly slice the hamachi. Get some plastic wrap and pound out the hamachi with a hammer or mallet until very thin. Place slices on a plate. Heat up some simple syrup, or 1/3 cup water and 1/3 cup sugar. Slice kumquats thinly and put them in the simple syrup pan and candy for a four to five minutes. Julienne the shiso leaves.
Place some of the kumquats and shiso on top of the hamachi. Sprinkle with olive oil, salt and pepper.