Balsamic beef stew with veggie mash

Name: Balsamic beef stew with veggie mash
Prep time: 20 min
Cook time: 3 h 10 min
Total time: 3 h 30 min
Cuisine: European
Ingredients: 1 tbsp olive or rapeseed oil; 2 large onions (325g), halved and sliced; 600g diced lean stewing beef; 2 garlic cloves chopped; 10g dried porcini mushrooms; 2 tbsp balsamic vinegar; 2 tbsp tomato purée; 2 tsp vegetable bouillon powder; 1 tsp English mustard powder; 320g carrots finely chopped; 200g large chestnut mushrooms quartered; few fresh thyme sprigs; 4 x 80g portions broccoli cut into florets; 750g swede cut into chunks; 500g potatoes cut into small chunks