Marinated Tuna with Baguette

1 Lemon
1/2 cup Extra virgin olive oil
1/4 cup Sherry vinegar
1 small Red onion (Halved thinly sliced)
2 oz. Brine-packed picholine olives
3 tbs Fresh oregano
2 jars Oil-packed tuna
  Course salt and freshly ground pepper
1 Baguette

Remove lemon zest in strips using a vegetable peeler, and slice lengthwise into thin strips; reserve lemon for another use.

Combine zest strips with oil, vinegar, onion, olives, and oregano in a shallow dish. Mix in tuna and season with salt and pepper. Refrigerate for 30 minutes. Serve marinated tuna with baguette. Mango salsa on the side.