Combine all the dressing ingredients in a small bowl. Whisk thoroughly for 2-3 minutes until all the ingredients are well combined or place all the ingredients in a jar with a lid and shake until well combined.
Place the spinach in a large bowl or individual serving bowls.
Add the strawberries and red onions on top for the salad mixture.
The drizzle the dressing over the salad and toss to thoroughly coat. You want enough dressing to coat the ingredients but not drown them.