In a shallow platter, combine the bread crumbs and chorizo pieces, mixing to distribute evenly. Cut the tuna into 2-inch thick slices. Press only 1 side of each tuna fillet into the bread crumb mix. In a saute pan over medium heat, add 1 tablespoon of oil. Sear the breaded side of the fillet. Turn over and sear the other side for 2 minutes (keeping it rare) and reserve. To the pan, add the remaining olive oil and saute the garlic until fragrant. Pour in the vinegar and white wine, and reduce the liquid by half. Whisk in the butter and remove the pan from the heat. Season with salt and pepper.
To serve, place the potatoes on the center of a plate, stack the tuna fillet on top and add sauce lightly over and around the tuna.
In a small saucepot, add the red potatoes and enough water to cover and add a generous amount of salt. Bring to a boil, then reduce to a simmer. When the potatoes are tender, strain and allow to cool. Cut the cooled potatoes in half. Heat the oil in a small saute pan over medium-high heat and then add the potato halves, cut side down. Cook until golden on 1 side, then turn over and cook the other side. Drain onto paper towels, season with salt and pepper, and reserve.