In the bowl of a food processor (or mixing bowl) place the flour, sugar, baking powder, and ½ tsp salt and pulse to combine (or cut in with pastry cutter, or pulse on and off using beater blade in a stand mixer).
Add cold pieces of butter and pulse until butter is cut into small pieces.
Add vegetable or canola oil and pulse again to combine.
Slowly add water until the mixture comes together. It will almost look like a thick buttercream frosting (it will be sticky and too wet looking).
Remove the dough and place it on a sheet of plastic wrap. Wrap it well and refrigerate it for at least two hours, but up to 3 days.
Preheat the oven to 400° F.
Roll out the dough on a lightly floured surface to about ⅛-inch thick. Cut out with a small 1½-2 inch fluted biscuit cutter and place on parchment-lined baking sheets about 2 inches apart.
Refrigerate for 30 minutes.
Using the blunt end of a wooden skewer (or other similar object), poke several holes in the tops of each cracker.
Bake for 15-20 minutes, or until crackers are evenly browned and crisp. They will crisp a little more after cooling.
Mix 1 tsp of salt with the 3 tbsp of melted butter and brush on tops of crackers immediately upon removing from the oven.
Store in sealed glass container for about one month. Re-crisp if necessary in a 350° F oven for about 5 minutes.