Make the empanada dough:  In the bowl of a stand mixer fitted with the dough hook attachment, combine flour, softened butter, sugar, and salt on medium speed until thoroughly blended. With the motor running, slowly add in cold water and mix until a soft and pliable dough forms, 7 to 10 minutes.

Transfer to a clean work surface lightly dusted with flour and kneaded one or two times, just enough to form a neat ball. Wrap in plastic wrap and set in the refrigerator for 4 hours up to overnight.

On an un-floured flat work surface, roll out the dough into a ⅛ inch thick sheet; let the dough rest for 10 minutes. Then, cut out the disc using a 5 to 6 inches rounds cutter or saucer; depending on how large you prefer, I use a 6'' glass lid.

Then, gather the scraps, add to the rest of the dough, and roll out another batch of circles; repeat with the rest of the scraps. Cover the discs with cling film and chill while you prepare the filling or if not used immediately, use wax or parchment paper to separate the stack and refrigerate or freeze to use later.

Place eggs in a pot of water on the stovetop with at least an inch of water covering the eggs. Simmer the eggs. Turn on the heat and bring the water to a rolling boil. Simmer the eggs in boiling water for fifteen minutes to get firm whites and egg yolks.

Using a slotted spoon, remove the eggs from the pot and place them in an ice bath in a large bowl. Cooling the eggs in cold water will halt the cooking process and make handling the eggs easier when peeling.

When the eggs are completely cool to room temperature—about fifteen minutes—gently tap the egg on the counter or table to crack the peel. Tap the top end of the egg and the bottom end before tapping the egg's sides to break up the eggshell.

Carefully peel the egg, starting from the wide bottom end of the egg to break the air pocket between the egg and the shell. Then, gently peel off the shell to avoid breaking the egg whites. Pat, dry with a paper towel, and places them into a bowl. Using a fork, mince the eggs, cover with plastic wrap, and store in the refrigerator until ready to use.

Before starting with the filling, let the dried tomatoes soak in warm water for 30 minutes until soft and pliable; drain, pat them dry, and finely chopped. Carefully grate the fresh tomato and discard the skin; set aside.

Heat 1 tablespoon of extra virgin olive oil in a large skillet over medium heat. Add the onions, pepper, garlic, and white part of the scallions, season with salt, and cook until soft and translucent, 8 to 10 minutes.

Add the grated tomato and sliced olives and saute for 5  minutes to eliminate any excess liquid; the mixture should be moist but not runny. Add the canned tuna, paprika, oregano, red pepper flakes, and cumin. Add the finely chopped dried tomatoes and the green part from the scallions and mix well. Taste and adjust seasoning if needed. Cook for a few seconds, then turn off the heat.

Mix in the minced eggs, then transfer to a large bowl. Let it cool to room temperature, then cover and refrigerate until ready to use.

Position 2 racks in the middle of the oven and preheat the oven to 425 degrees F. Line 2 large baking sheets with parchment.

Spoon about 2 spoonfuls in the middle of each empanada disc, leaving a 1-inch border around the edge; avoid reaching the edges with the filling because oiliness will prevent a good seal.

Moisten the tip of your finger with a small amount of water and moisten the edges of the circle with your finger around half the border, then fold the dough over and press the edges together to seal and create a half-moon shape.

Pleat the edges or crimp with a fork, removing any air pockets as you go. Repeat with the remaining rounds and filling. Let the empanadas rest in the fridge until you're ready to bake.

In a small bowl, lightly beat the egg yolk (do not beat until ready to bake) with 1 tablespoon of heavy cream, whole milk, or water, and a pinch of salt and sugar.

Lightly brush the top of the Tuna empanadas with the egg mixture.

Bake the tuna empanadas in the oven for about 20-25 minutes, until golden on top. Serve the tuna empanadas warm with chimichurri sauce and a side of yucca, if desired. Enjoy!