There's a super speedy, super spicy tomato one over on the recipe bit, but if you make a base of softened onions, celery and carrots, add a can of tomatoes and a tetra of passata you can then chuck in some stock-cube-stock and whatever SS veggies you have in the fridge/freezer (I usually use frozen peppers, cabbage (red will turn your soup a slightly distressing purple, but it tastes nice), frozen spinach (will turn your soup brown), but anything that's speedy that you have will be fine with that base - more peppers, carrots and swede/turnip for sweeter, more leafy green very for less).