Prepare the dressing: Place the organic canola oil, orange juice, sugar ,poppy seeds, chopped onion, salt, and mustard powder in a jar with a lid. Shake well until combined.In a large bowl, place the spinach, sliced strawberries, and diced apples. Toss to combine.Pour â…” of the dressing over the salad and toss to coat. Add the remaining dressing if desired, or place on the table so more dressing can be added to individual servings if desired.