Slice onion and let sit for at least 5 minutes. Then after onion has sat for five minutes, marinate it in the apple cider vinegar and hot water for 10 minutes while assembling the rest of the salad. Rinse and dry baby spinach. If you have a salad spinner that is best, otherwise, dry with paper towels. This will avoid dressing getting diluted. Whisk together balsamic vinegar, honey, salt and pepper, drizzling in the olive oil a little at a time at the end. Toss with rest of ingredients and serve. Makes 4 servings.