Preheat your oven to 220 °C, 200 °C Fan, 425 °F, Gas Mark 7.
Peel potatoes and cut them into 1.5cm thick slices before cutting the slices to give 1.5cm x 1.5cm sticks. Cut each potato stick to produce 1.5cm cubes.
Rinse the diced potatoes in cold water and drain.
Place your drained potato cubes in a large microwaveable bowl. Microwave on full power for 4 minutes and then drain.
Evenly coat your diced potatoes with the oil.
Toss with crushed garlic so it becomes evenly distributed over the oiled potato cubes.
Sprinkle chopped rosemary, salt and half of the chopped thyme over your potatoes. Stir and turnover the potatoes so they are evenly coated with the herby garlic oil.
Grease roasting tin with a little oil before evenly spacing your potato cubes on it. Allow plenty of room for air circulation between the cubes. If you don’t have a roasting tin which is large enough, use two tins to achieve maximum crispness.
Place your roasting tin/s of potatoes into pre-heated oven.
Cook for 25 minutes, turning the potatoes after 15 minutes.
Serve straightaway with a sprinkling of sea salt and the remaining chopped thyme.