This salad combines, earthy, sweet, tart, and savory flavors.
In a large bowl, whisk together vinegar, mustard, and oil until combined and thickened; season with salt and pepper.
Add spinach, onion, and cherries; toss to combine. Serve immediately, topped with pumpkin seeds.
To toast the pumpkin seeds, spread in a single layer in a pie plate; bake in a 350-degree oven until puffed and brown, about 10 minutes.