Dice onions and garlic, fry in olive oil until lightly browned
Finely chop or grate mushrooms and carrots (I used a food processor) and add to the pan
Fry until mushrooms have lost their moisture and add the drained, mashed beans (keep the bean liquid if you're making the vegan duchess potatoes as a side!)
Add tomato paste, mustard and flax egg / broth mixture.
Season to taste, then set aside to cool down.