Warm oil in a large saucepan over medium heat. Add onion, pepper, celery, salt, and chili powder and saute until softened, 6-8 minutes. Stir in potatoes, corn, almond milk and broth. Increase heat and bring to a boil. Reduce to a low simmer and cook for 15 minutes or until potatoes are tender.
Carefully transfer half of the soup to a blender and process until creamy and smooth. Return to pan with remaining soup, stir and simmer an additional 10 minutes. If desired, garnish with green onions.