For the dressing, push a straw through the strawberries from the tip to the green top to remove the hull. (Or you can cut it off with a knife!)
Add the rest of the dressing ingredients, and blend until smooth. Refrigerate.
Cut strawberries, apple, and onion into slices.
Combine all the salad ingredients in a large bowl, drizzle with desired amount of dressing and toss to coat. (Spinach wilts easily, don't add dressing until ready to eat!)