Add almond flour, coconut flour, xanthan gum, baking powder and salt to food processor. Pulse until thoroughly combined. 

Pour in apple cider vinegar with the food processor running. Once it has distributed evenly, pour in the egg. Followed by the water. Stop the food processor once the dough forms into a ball. The dough will be sticky to touch.

Wrap dough in cling film and knead it through the plastic for a minute or two. Think of it a bit like a stress ball. Allow dough to rest for 10 minutes (and up to two days in the fridge). 

Break the dough into eight 1” to 1 1/2” balls. Roll out between two sheets of parchment or waxed paper using a tortilla press (suggested) or with a rolling pin. The dough should be VERY thin as it'll puff up considerably when cooked. For your reference, each tortilla should weigh 26g uncooked. 

Preheat oven to 320°F/160°C.

Heat up a pot or frying pan over medium/high heat and add lard or frying oil of choice (a centimeter or so will do). Once hot, drop the tortillas in batches. Cook briefly until they just begin to brown, and flip them over immediately. Transfer to a paper towel lined plate. You want to keep your taco shells as white as possible, as they'll continue to brown when baked. 

Make the curved taco shells by placing the fried tortillas half-curled in an upside-down muffin pan. Bake for 30 to 40 minutes until golden and crisp. Be sure to check in on them every 10 minutes or so the first time around. 

Preheat oven to 320°F/160°C.

Make the curved taco shells by placing the raw tortillas half-curled in an upside-down muffin pan. Bake for 35 to 40 minutes until golden and crisp. Be sure to check in on them every 10 minutes or so the first time around.

Store in an airtight container for 3-5 days.