Mix 1 cup flour, water, and salt together to make a soft dough. Spray dough and work surface with olive oil; knead dough until smooth but still a little sticky.

Set dough aside and cover with a warm, damp cloth. Let dough rest for at least 10 minutes.

Preheat a large griddle while rolling out the tortillas.

Divide dough into 8 equal parts. Form into smooth balls and flatten the tops. Roll balls in 1/4 cup flour and roll out into 6-inch circles. Dust rolling pin or work surface very lightly with flour if dough sticks. Brush tortillas with vegan margarine on one side.

Place tortillas on the preheated griddle greased-side down. Cook until tortillas change color and start puffing up, about 10 seconds. Flip over and press puffed parts lightly with a flat spatula. Flip again. Cook just until golden-brown spots appear on both sides; tortillas should still be soft and pliable.

Keep tortillas stacked together on and under a cloth to keep from drying out.

Pulse cauliflower florets in a food processor until chopped into rice-sized pieces.

Heat olive oil in a large skillet over medium-high heat. Cook cauliflower, onion, and serrano pepper until softened, about 5 minutes. Mix in ketchup, chili powder, and cumin.

Process black beans in the food processor until smooth. Stir into the cauliflower mixture until heated through, about 5 minutes. Season with salt and pepper. Use 1/4 cup of the mixture for each tortilla.