Combine the water and butter in a medium saucepan over medium heat, allowing the butter to fully melt. In a large mixing bowl, whisk together the flour, salt, and paprika. Create a well in the center and pour a portion of the warm butter mixture into it, mixing with your fingertips to form a wet paste. Gradually add the remaining liquid, working the dough with your hands until it becomes wet and oily. Wrap the dough in plastic wrap and refrigerate for at least 2 hours.

Preheat your oven to 400°F. Prepare a large baking sheet by lining it with parchment paper or a silicone baking mat.

Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the ground beef, cooking until it is browned, which should take about 10 minutes. Use a slotted spoon to remove the beef, setting it aside while reserving 2 tablespoons of the drippings.

In the same skillet, add the remaining tablespoon of olive oil and the reserved drippings. Sauté the minced yellow onion until it turns translucent, about 10-15 minutes. Add the finely diced bell peppers, peas, garlic, and seasonings.

After a few minutes, deglaze the pan by adding the beef broth, then mix in the tomato paste to your preference. Once the tomato paste has fully dissolved, incorporate the browned beef and boiled potatoes into the mixture. Remove the skillet from the heat.

Divide the chilled dough into golf-ball-sized portions, rolling each into a ball. On a lightly floured surface, use a rolling pin to flatten each ball into a 1/4-inch thick circle, about 5 inches in diameter.

Place 2 heaping tablespoons of the filling in the center of each dough circle. Add ½ teaspoon of chopped scallions to each, and sprinkle lightly with cheese if desired. Brush a small amount of the egg wash on one half of the dough’s edge. Fold the dough over to create a half-moon shape, pressing the edges firmly to seal. Crimp the edges with the back of a fork.

Arrange the empanadas on the prepared baking sheet. Lightly beat together the egg and water, then brush this egg wash over the empanadas.

Bake the empanadas until they turn golden brown, approximately 20 minutes. Serve them warm.

Store leftovers by wrapping them in plastic or placing them in an airtight container in the refrigerator for up to 3 days. For longer storage, freeze cooked empanadas wrapped in plastic inside a resealable freezer bag or airtight container for up to 3 months. To reheat, unwrap the desired number of empanadas and warm them in a 300°F oven or toaster oven for about 10 minutes.