In a large mixing bowl, blend together the all-purpose flour, baking powder, salt, and shortening until the mixture resembles coarse crumbs.

Gradually add in the milk, stirring until a soft dough forms. Transfer the dough to a floured surface and knead lightly until it becomes smooth, about 2-3 minutes.

Roll the dough into a loaf about 8 inches long, then cut it into 8 equal pieces. Flatten each piece into a round disk, roughly 4-5 inches wide.

In a heavy-duty skillet, heat about 2 inches of canola oil over medium-high heat until it's shimmering.

Carefully place half of a dough circle into the hot oil. Fry for about 30–60 seconds before flipping it over. Cook until golden brown on both sides, approximately 2 minutes total. Remove and drain on paper towels.

Load each crispy chalupa shell with your choice of seasoned ground beef, cheese, lettuce, diced tomatoes, and a generous dollop of sour cream. Serve immediately for optimal freshness.