Steam potato slices, covered, for 10 minutes. Add carrot; cover and steam an additional 5 minutes. Set aside.
Heat a small nonstick skillet over medium heat until hot; add artichokes and sauté 3 minutes. Combine potato slices, carrot, artichokes, and onions in a large bowl; toss gently. Combine vinegar and next 5 ingredients; stir well with a wire whisk. Pour over vegetables, tossing gently to coat. Serve salad warm.