Carol and I were recently in Galicia walking the Camino de Santiago. In Galicia, empanadas were commonly available at both restaurants and bakeries, and tuna is by far the most common filling. (If the filling is not specifically identified, you can be confident that it is tuna.)
This version is a large empanada to be cut into wedges, and is adapted from SeriousEats.com, which is one of my favorite cooking websites . I baked it in a large paella pan as an appetizer for a family Memorial Day gathering. I used 3 cans of the oil packed canned tuna available at CostCo.
12-3/4 oz. all purpose flour
1-1/2 tsp. kosher salt
1 tsp. yeast
2 Tbs. extra virgin olive oil
8 oz. warm water
6 Tbs. extra virgin olive oil
2 large peppers, thinly sliced
4 cups chopped onions
15 garlic cloves, thinly sliced
15-17 oz. oil packed canned tuna, drained
Salt and pepper
Mix together the flour, salt, and yeast. Add the olive oil and the water. Mix to form a dough. Rest covered for 15 minutes, and then knead with the dough hook in the bowl of a stand mixture for about 5 minutes, or until a smooth dough is formed. Coat lightly with oil and put in a covered container to double, which will be in 1-2 hours.
While the dough is rising, make the filling. Put the olive oil into a large frying pan and add the sliced peppers. Cook over medium heat for about 5 minutes taking care not to brown the peppers. Add the onions and garlic and continue to cook until all of the vegetables are very soft and sweet, about 25 minutes in total. Remove from the heat. Add the tuna, and mix well with the vegetables. Add salt and pepper to taste and allow to cool to room temperature.
Preheat the oven to 350 degrees.
Divide the risen dough into two pieces, a slightly bigger piece for the bottom crust and a slightly smaller piece for the upper crust. Roll out the bigger piece into a circle about 14 inches in diameter. I used a large paella pan as a baking dish. Spread the filling out on top of the bottom crust. Roll the smaller piece of dough out into a circle large enough to cover the filling. Pinch the two layers together. Pierce the upper layer with some holes to vent the steam when the empanada bakes. Bake the empanada until the crusts are fully cooked, about 45-55 minutes.
Cool and cut into slices. In Galicia this is normally served at room temperature.