Steam the vegetables; cook them in boiling water or in a microwave until they are just tender. Drain them well.
Meanwhile heat the oil in a large pan and stir in the flour. Add the garlic and the tomatoes, butter beans, yeast extract and herbs and stir well together. Gently stir in the cooked fresh vegetables. Check for seasoning and add salt if required and freshly ground black pepper.
Place mixture in an oven-proof dish
To make the topping, melt the margarine, stir in the oats, sesame seeds and nuts and about two thirds of the cheese.
Sprinkle the topping over the vegetables and sprinkle the remaining cheese over the top. Bake for 20 minutes at 375 F (190 C) (gas mark 5) until the cheese has melted and the top is golden brown.
If preferred, not necessarily a health suggestion, short crust or puff pastry can be used for the topping in place of the crumble.