Here's a quick and colorful dish that's just right for serving family style, preferably with crusty bread to sop up the juices. To make it, you simply cut tuna into cubes and sprinkle with breadcrumbs and eventually add the cooked potatoes, roasted bell pepper, and sliced pitted olives, then sprinkle with chopped cilantro, drizzle with olive oil, and bake just until the fish is cooked through, being careful not to overcook.