Mix both flours, garlic powder, curry powder, baking powder, and salt in a large bow.
Make a well in the center and add the tahini and 1/3 cup of water. Stir with a wooden spoon, then with your hands to form a ball. If the dough is not coming together, add a tiny bit of water. Press into a rectangle, wrap in plastic, and refrigerate for about an hour.
Preheat the oven to 350°F/180°C.
Line a baking sheet with parchment paper.
Remove the dough from the refrigerator and place it between two sheets of parchment paper. Roll out the dough into about a 12-by-13-inch (30 x 32 cm) rectangle. The dough should be thin and even.
Brush dough lightly with olive oil. Sprinkle the topping. Cut dough into desired cracker shapes using a sharp knife or a pizza cutter. Prick the crackers with a fork.
Transfer the crackers to the prepared sheet pans. Be careful not to crowd the crackers.
Bake in the oven for 15-20 minutes or until golden brown. If the crackers along the edges bake faster, transfer them to a cooling rack and allow the remaining crackers to bake.
Transfer crackers to cooling rack. Crackers will crisp as they cool. Serve crackers immediately or store them in an airtight container on the counter for up to a week.