Pre-heat oven to 400 deg. Chop veggies (sweet potatoes, zucchini, red peppers) roughly and arrange veggies on a baking tray, brush with some oil and roast for about 30 mins (10 mins longer for sweet potatoes).
Heat some oil in a dutch oven, add chopped onions and grated ginger. Fry for a minute, add roasted veggies and mix well. Add vegetable stock, and then blend with immersion blender. Add salt, pepper, a tsp of dried oregano and more stock if needed. Heat through, add fresh lemon juice and garnish with green onions.