Bring a medium pot of water to a boil. Meanwhile, peel carrots and trim tops to 1/2 in.
Boil onions 3 minutes; drain and cool in a large bowl of cold water until no longer warm. Cut off their root ends and peel them (often they'll just pop right out of their skins).
In a large nonstick frying pan, combine onions, carrots, sugar, butter, salt, and enough water to come about halfway up vegetables. Cover and cook over medium-high heat, 5 minutes.
Uncover and cook, stirring frequently, until onions and carrots start to brown and are tender-crisp, 5 to 10 minutes longer.
Note: Nutritional analysis is per serving.