In a large bowl, add the potatoes, garlic, chili peppers, a pinch of parsley, salt, and black pepper, to taste. Add 3/4 cup of olive oil and mix well. Spread the potato mixture on an ovenproof pan, packing the mixture so it serves as a solid bed for the tuna.
Spread half of the fennel seeds, lemon rinds, basil and pieces of plum tomato sparingly on top of the potato mixture. Add the tuna slices on top, covering the baking dish. Spread the remainder of the lemon rinds, crushed fennel seeds, and pieces of plum tomatoes on top of the tuna. Generously sprinkle with the bread crumbs, and drizzle the remaining extra-virgin olive oil on top.