Scrape the carrots and slice or dice. Place in a saucepan and add the onion, bay leaf, sugar, butter and water. Cover with a lid and bring up to the boil, then cook over moderate heat. After about 20 minutes the carrots should be tender. Remove the pan lid and continue to boil quickly so that the water remaining in the pan evaporates.
When the carrots begin to fry in the butter glaze that remains, draw them off the heat. Toss them, check the seasoning and serve in the shiny butter glaze. If you add peas, do so towards the end of cooking time as they take less time to cook than carrots.