In a large mixing bowl, combine all-purpose flour and salt. Cut in cold butter until the mixture resembles coarse crumbs. Gradually add cold water, mixing until the dough holds together. Form into a ball, wrap in plastic, and refrigerate for 30 minutes.

In a skillet over medium heat, sauté onions and bell peppers until softened, about 5-7 minutes. Stir in ground beef, breaking it up as it cooks. Season with smoked paprika and fresh herbs. Cook until the beef is browned and fully cooked, approximately 10 minutes, then let cool.

Preheat your oven to 350°F (175°C). Roll out the dough into thin sheets and cut into circles. Spoon a small amount of the filling onto one half of each circle, fold over to enclose filling, and seal the edges.

Place assembled empanadas on a lined baking sheet. Brush with egg wash if desired, or leave unbrushed for a vegan option. Bake for 25-30 minutes, or until golden brown and crisp.