Preheat the oven to 360ºF/ 180°C.
For the filling, sautee the red pepper for five minutes in a pan coated with a dash of olive olive. Add the zucchini and cook for another 5 minutes. Mix in the tuna, olives, salt and pepper and set aside.
In a bowl combine rice flour, corn flour, starch and baking powder. Mix in the turmeric (optional). Gradually mix in the egg, olive oil and milk, stirring frequently. Finish with the green onion tops and parsley and give it all a gentle stir.
Finally add the tuna and pepper mixture to the dough and transfer everything to a 0,5kg/1lb loaf tin lined with parchment paper.
Bake in the middle of the oven for 30 to 45 minutes or until golden and the tip of the knife comes out clean.