Begin by thoroughly washing and drying the baby spinach. It is important that the leaves are dry so the dressing clings to them properly. Thinly slice the red onion into half-moons. If you find raw onion too sharp, soak the slices in cold water for five minutes then pat them dry to mellow the flavor.
Place the pecan halves in a small dry skillet over medium heat. Stir them frequently for about 3 to 5 minutes until they become fragrant and slightly darker in color. Remove them from the heat immediately to prevent burning and let them cool before adding them to the salad.
In a small bowl or a glass jar with a tight lid, combine the olive oil, apple cider vinegar, honey, Dijon mustard, salt, and pepper. Whisk vigorously or shake the jar until the ingredients are fully emulsified and the dressing looks smooth and slightly thickened.
In a large serving bowl, layer the spinach, dried cranberries, sliced red onions, and toasted pecans. Sprinkle the crumbled feta cheese over the top. Wait to add the dressing until you are just about ready to sit down for your meal to ensure the spinach stays crisp.
Drizzle the dressing over the salad starting with about half of the mixture. Use salad tongs to gently toss the ingredients until every leaf is lightly coated. Add more dressing if needed, then serve immediately while the textures are at their peak.
