1. Pour quinoa into a fine strainer and rinse well under cool running water.
2. In a 1 1/2- to 2-quart pan, combine quinoa and 2 cups water. Bring to a boil on high heat, turn heat low, cover, and simmer until grain is tender to bite, 10 to 15 minutes. Let cool.
3. Meanwhile, combine vinegar, apple juice concentrate, allspice, pepper, and garlic. Mix with cool quinoa.
4. Core apple and cut in 1/4-inch cubes. Mix apple, carrot, onion, and mint with quinoa.
5. Mound salad on a lettuce-lined platter. Add salt to taste.