Prepare carrots:
Whisk together sugar, lemon juice, spices, salt, and oil in a large bowl until sugar is dissolved.
Halve carrots crosswise on a long diagonal, then, starting from diagonal ends, cut into 1/16-inch-thick slices using slicer. Cook carrots in a 4- to 5-quart pot of boiling salted water until crisp-tender, about 45 seconds. Drain well in a colander and immediately toss with dressing. Cool to room temperature, stirring occasionally, then marinate, covered and chilled, at least 4 hours.

Spread tapenade on 6 slices of bread and goat cheese on remaining 6 slices, then make sandwiches with carrots.