In a large bowl, mix the wheat flour and salt. Add the butter or margarine and mix with your hands until you get a sandy texture.
Gradually add the warm water, little by little, while mixing with your hands. Continue kneading until you obtain a smooth, elastic dough. If the dough is too dry, add a little more water, one tablespoon at a time. If it is too sticky, add a little more flour.
Transfer the dough to a lightly floured surface and knead for about 5-7 minutes, until the dough is smooth and elastic.
Form the dough into a ball, place it in a bowl and cover it with a damp cloth. Let rest for at least 30 minutes to relax the dough and make it easier to handle.
After the resting time, divide the dough into smaller portions, about the size of a golf ball. This will make it easier to roll out the dough and fill the pastelitos.
Take a portion of dough and, using a rolling pin, roll it out on a lightly floured surface into a thin circle approximately 10-12 cm in diameter.
Place a spoonful of filling in the center of the dough circle. Fold the dough in half, forming a semicircle, and press the edges with your fingers to seal them. You can use a fork to score the edges to make sure they are well sealed.
Repeat this process with the rest of the dough and filling.
Heat enough vegetable oil in a skillet over medium-high heat. Make sure the oil is hot enough before frying the pastelitos .
Fry the pastelitos in batches, taking care not to overcrowd the pan. Cook the pastelitos for about 3-4 minutes on each side, or until golden brown and crisp.
Remove the pastelitos from the pan and place them on paper towels to remove excess oil.