To make Tuna Fish Cakes, start by draining the canned tuna.
While the rice is cooking, prepare the eel by grilling or frying it.
Put the tomato paste, olives, and butter into a blender or food processor and whizz until smooth.
Put the oats in the blender or food processor, slightly broken up.
Coat the fillets with the butter mixture while grilling.
Heat a large skillet over medium-high heat and add the fish cakes.
Serving Suggestions: Squeeze the lemon juice over the top, sprinkle with chopped parsley and smoked paprika and serve with the butter beans and tomatoes on the vine.