Japanese Sweet Potato Okonomiyaki

Name: Japanese Sweet Potato Okonomiyaki
Prep time: 10 min
Cook time: 25 min
Total time: 35 min
Yield: Makes 3 large pancakes
Ingredients: 1 cup plain flour; ½ tsp baking powder; ¾ cup vegetable stock; 3 eggs; 1 tbsp soy sauce; 3 cups shredded Chinese cabbage (also called wombok or Napa cabbage); 100g (3.5 oz) sweet potato, peeled, coarsely grated; ¼ cup finely sliced spring onions (scallions), plus extra to sprinkle; ½ cup vegetable oil; Japanese tonkatsu sauce* to serve; Japanese Kewpie mayonnaise* to serve; Nori flakes or nori furikake* to serve