Begin by cutting the carrots into 1½ inch (4 cm) chunks, but no smaller.Next, dry roast the coriander seeds and peppercorns in a small frying pan or saucepan over a medium heat, stirring and tossing them around for 1-2 minutes, or until they begin to look toasted and start to jump in the pan. Now empty them into a pestle and mortar and crush them coarsely, then put the carrot chunks and crushed spices in a bowl. Next, put the garlic cloves and salt in the mortar, crush to a purée, then whisk in the oil. Now toss this mixture around with the carrots and spices, then spread it out on the baking tray.Pop it into the oven on a high shelf and roast until the carrots are tender when tested with a skewer – 30-40 minutes.