Cook prawns and peas in a large pot of salted boiling water, for 4 mins. Drain and gently pat dry.
In a large bowl, mix together cooked rice, egg whites, lemon zest and chili flakes and season a little.
Fold in chopped onions, diced ham, sesame seeds, panko, prawns and peas, mix and season to taste.
With the help of your hands, shape the rice mixture into round, flat patties.
Arrange some extra panko onto a plate and lightly coat both sides of each cake. Refrigerate for 5 mins.
Heat a large frying pan, add the oil and swirl it around to coat the bottom.
Stir fry the rice cakes for 2 mins on each side, or until golden.
Pat dry on kitchen paper and serve immediately.