Veggie sausage and bean pasta sauce

One of my favourite pasta sauces. For the veggie sausages, I use my favourite type which are so good I've cooked them for meat-eaters before and they didn't know the difference, but any other type would work too. This is enough for 4 servings.

Ingredients:
6 Linda McCartney vegetarian sausages
6 mushrooms
A slice of butter
1 onion
1 clove of garlic
1 tablespoon of sugar
1 can chopped tomatoes
1 can kidney beans
1 can butter beans
1 vegetable stock cube
2 tablespoons mustard
1 tablespoon of mixed herbs
1 tablespoon tomato puree
Salt
Pepper
A little olive oil

Cooking:
1) Fry the veggie sausages in the olive oil in a deep pan until golden brown. After they're done take them out and keep them seperate for now.
2) Finely chop the onion and the garlic.
3) Chop the mushrooms into thin slices.
4) Add the butter to the pan and put in the chopped onion and garlic, the spoonfuls of sugar and mixed herbs and a little salt and pepper. Cook on medium temperature and keep stirring until the onions are well softened.
5) Once they're ready, add the can of chopped tomatoes, 2 spoonfuls of mustard and the chopped mushrooms.
6) Melt the vegetable stock in a little hot water and add it, stirring it well into the sauce.
7) Put on a lower temperature and put a lid on the pan, leave it to cook for 20 minutes.
8) While that's cooking, chop the sausages into quarters.
9) Taste the mushrooms to see if they're cooked enough, re-cover and cook for longer if necessary.
10) When they're done, add the chopped sausages, the cans of butter beans and kidney beans, and the spoonful of tomato puree. Stir well.
11) Cover it again and cook for 10 more minutes on low temperature.