Cook rice, following absorption method on packet. Set aside to cool.
Preheat oven to 200°C Heat oil in a non-stick frying pan over medium heat. Add onion and garlic. Cook, stirring, for 3 to 4 minutes or until soft. Remove to a bowl. Add rice, tuna, semi-dried tomato, cream, egg and dill. Season with salt and pepper.
Place 1 pastry sheet on workbench. Brush with butter. Top with another pastry sheet and brush with butter. Repeat to form 3 layers. Cut pastry lengthways into thirds.
Spoon 1 heaped tablespoon tuna mixture onto short end of each pastry strip. Fold pastry over filling to form a triangle. Continue to fold triangle over itself, down length of pastry strip. Brush with butter. Place on a greased baking tray. Repeat with remaining pastry, butter and filling.
Bake triangles for 15 to 20 minutes or until pastry is golden. Set aside to cool.