Method

1. In a 3-quart saucepan cook onion in hot oil over medium heat for 5 minutes.
2. Add broth and pepper.
3. Bring to a boil.
4. Add potatoes and return to a boil, reduce heat. Simmer, covered 10 minutes.
5. Meanwhile, in a large skillet cook mushrooms in butter over medium heat 6-8 minutes until tender and liquid has evaporated; set aside.
6. Remove saucepan from heat.
7. Use immersion blender to blend onion-potato mixture until almost smooth.
8. Add spinach, arugula and parsley.
9. Return to heat.Bring to boiling; remove from heat.
10. Using immersion blender, blend soup again until nearly smooth and flecks of green remain.
11. Season to taste with sea salt.
12. Serve immediately, topped with sautéed mushrooms and additional fresh arugula.