Now prepare the tuna. Heat a large cast iron griddle pan over high heat. Drizzle the tuna with olive oil and season with salt and pepper. Place on the hot grill for about 45 seconds and then turn over and do the same. The tuna should be rare on the inside and have nice grill marks on the outside.
To serve, smear a spoonful of the white bean puree on the bottom of a plate. Top with a the tuna and a spoonful of tapenade over the top. Set a cluster of the roasted tomatoes over the top and drizzle the juices from the pan all around the plate. Garnish with fresh arugula leaves.