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