Place pineapple slices and shishito peppers separately on a foil lined baking pan and coat evenly with oil. Place ingredients in oven at 400 degrees until caramelized, at least 5 minutes. Take out and chop pineapple into small pieces about 1/8 inch thick. Let both ingredients cool for 10 minutes.
In a medium bowl, combine Ahi tuna, soy sauce, mae ploy, pineapples, green onions, sesame oil, sesame seeds and half of shishito peppers; mix well. Refrigerate at least 2 hours before serving. Top with remaining shishito peppers.
Serve on a bed of steamed rice with layered avocado.