Heat oil in large saucepan or Dutch oven over medium-high heat. Add carrots, and sauté 5 to 7 minutes, or until beginning to brown. Add maple syrup, mustard, and 1 cup water; season with salt and pepper, if desired. Cover, reduce heat to medium, and simmer 10 minutes, or until carrots are tender. Uncover, increase heat to medium-high, and simmer 5 minutes, or until liquid is syrupy and carrots are glazed. Stir in tarragon just before serving.