Whisk flour, salt, and baking powder together thoroughly in a large mixing bowl, or in the bowl of your stand mixer.
Add the canola oil, sourdough starter, and water and thoroughly mix. To full incorporate the wet and dry ingredients, you might need to use your hands. Using your hands, knead and fold the dough until all the ingredients are fully incorporated and the dough is smooth. If using a stand mixer, mix the ingredients on medium speed with the dough hook attachment until fully combined. Once the dough starts to wrap around the dough hook, turn the speed down to low and continue to mix until the dough becomes smooth.
Turn the dough out onto a lightly floured work surface and divide into 16 equal pieces. If you want larger tortillas, you can divide into 8 larger, equal pieces.
Roll each piece of dough into a ball and let rest, covered in a damp towel, for at least fifteen minutes.
Once the dough has rested, warm a large frying pan on medium heat. Do NOT add any oil or grease to the pan.
Flatten each dough ball with a heavy rolling pin. Flatten and stretch each dough until they are circles approximately 6" in diameter. Do not worry about making them perfectly round!
Once the frying pan is hot, place one (or two, if your pan has room) tortilla into the pan and cook for 45 seconds or until the first side has become lightly browned. You will notice some bubbling, but if any of the bubbles become too large, you can prick them with a fork before you flip over the tortillas.
After ~45 seconds, flip the tortillas over and cook for 15-20 seconds on the reverse side, until brown spots form on the surface of the tortilla.
Once cooked, transfer the warm tortillas to a plate to cool.
Repeat with the 15 remaining tortillas.
Tortillas can be served immediately, while still warm, or transferred to an airtight container for several days. To reheat tortillas, place uncovered in the microwave alongside a small glass of water. Microwave for 20-30 seconds. The water will keep the tortillas from drying out while reheating.
To freeze tortillas for later use, place in a zip top bag with a sheet of parchment paper in between each tortilla. Tortillas will keep in the freezer up to two months.