Preheat your oven to 400 degrees Fahrenheit.
Thinly slice the onion and place them in a bowl. Pour the coconut milk and lemon juice in the bowl and mix. Let the onions soak for about 30 minutes.
Combine the almond flour, tapioca starch, garlic powder, salt and pepper in a dish. In batches, dip the soaked onions into the almond flour mixture to coat them, then carefully place them onto a parchment-covered sheet pan. Bake for 10-15 minutes on both sides, or until the onions and browned and crispy.