In a large bowl, mix the wheat flour, pureed yam and plant-based milk to form a batter. Add the garlic, cabbage, onion, smoked tofu, spring onion, salt and ground black pepper, and mix well.
To make the okonomiyaki sauce, mix the chuno sauce, vegan oyster sauce, tomato sauce and maple syrup in a small bowl.
Heat a non-stick frying pan over medium heat. Add 2 tablespoons of the canola oil and tilt the pan a little so the oil covers the base of the pan evenly. Add half of the batter and, using a spatula, press it into a flat pancake about 1 cm (½ in) thick.
Cook for 1 minute, then cover and cook for another 3–4 minutes, until lightly browned. Place a plate that’s larger than the frying pan over the pan, flip the pan carefully and slide the pancake back into the pan. Cook the other side for another 2–3 minutes, until lightly browned.
Regrease the pan with the remaining canola oil and repeat to make another pancake.
Brush the sauce on the top of the okonomiyaki, squeeze over the vegan mayonnaise, and sprinkle with aonori flakes and beni shōga to serve.