Meanwhile, roast and coarsely crush 1 tablespoon mustard seeds and 1 tablespoon cumin seeds. Combine flour, rice flour, cornstarch, 1tablespoon chilli flakes , 1 teaspoon dried herbs, 1/2 tsp. pepper, 1/4 tsp. garlic powder or chopped fresh garlic, 1 tsp. salt, crushed mustard and cumin seeds in a large bowl. Drain potato wedges and dredge potatoes in flour mixture, then transfer to another tray.