Combine the carrots and water in a saucepan, bring the liquid to a boil, and cook, covered, until the carrots are tender, 5 to 8 minutes.
Remove the carrots with a slotted spoon.
Over high heat, reduce the pan juices to about 1/4 cup.
Whisk in the syrup and dry mustard, and continue to cook over lowered heat, stirring constantly, for 3 minutes.
Add the walnuts.
Return the carrots to the pan until they are heated through and well glazed.