Pre-heat your oven to 220ºC and chop the potatoes into cubes. Finely chop the onion.
Drain the potatoes, add the chopped onion and sprinkle over the garam masala, onion granules, garlic granules, ginger, chilli powder, coriander, cumin and lime juice. Toss to coat. Spray with low calorie cooking spray so that all the potatoes are coated.