Place flour, baking powder, and salt in a large bowl and mix well. Next, add the shortening and, with the help of a fork, incorporate it with the flour until it resembles coarse oatmeal. Now, slowly pour the beer and stir to form the dough.
Place the dough on a floured work surface. Knead the dough for a couple of minutes until it is soft and smooth.
Place the dough back in the bowl and cover with plastic wrap. Let the dough rest for at least 30 minutes. This resting time will release the gluten that will help you roll the dough easily.
After the resting time, separate the dough into 16 equal pieces. They should be about the size of a golf ball and will correspond to one empanada each. Cover them with the plastic wrap while you roll one at a time to form the empanadas.
Lightly dust your work surface and rolling pin with flour and start rolling each piece of dough to form a 5-inch diameter circle. If you have a hard time forming a round shape, use a small bowl and place it upside down over the already-rolled dough, then gently press it down to cut the dough into a circle.
Once you’ve formed the circle, place 3 tablespoons of crab filling on one side of the circle and fold the empanada, making sure the edge of the top part will be about a centimeter behind the bottom edge.
Using a kitchen brush, very lightly moisten the edge with water. Now, pinch and fold the edges into half-inch sections towards the center, using your thumb and your middle and index fingers, overlapping each fold until you finish at the other end of the empanada.
Place the empanada over a clean kitchen towel and cover with plastic wrap, then proceed to form the rest of the empanadas.
Once all the empanadas are ready to be fried, heat the oil in a large frying pan over medium-high heat. Fry the empanadas, turning once, about 4 minutes per side until they are deep golden. Do not overcrowd your frying pan; for a 12-inch pan, fry 3 or 4 at a time, giving them enough room to turn them when ready. Remember, the oil is very hot, so be careful. Once ready, place them over the paper towel to drain or over a baking rack. You can eat them cold or warm. If you want to keep them warm, place them on a baking sheet in the oven at 250 degrees until you finishing cooking the rest of the empanadas.