Preheat oven to 425℉ (220℃).
Whisk flour, baking powder, and salt in a large bowl. Omit this step if using self-rising flour or baking mix already containing these ingredients.
Combine the flour mixture (or baking mix) with shortening until the mixture resembles coarse crumbs.
Mix the lemon-lime soda with the sour cream. Make a well in the biscuit mixture and pour in the sour cream mixture. Mix it until it holds together and becomes sticky, being careful not to overmix.
Turn your dough out onto a lightly floured work surface. Gently pat it out to about an inch thick. Cut out the biscuits with a biscuit cutter or a floured glass. Push straight down without twisting to ensure biscuits rise properly.
Pour most of the melted butter into a 9x13-inch baking dish, brushing to coat the baking dish evenly.
Place the biscuits in the baking dish and brush them with the remaining melted butter.
Bake for 10-12 minutes or until golden brown. Oven temperatures can vary, so watch them to avoid overbaking.
Remove the biscuits from the oven and let rest until they have absorbed all the butter. Enjoy!