• Heat the oil in a large casserole or deep frying pan.
• Peel the onion and slice into thick rings. Fry gently for a few minutes until softened.
• Cut the mushrooms into large chunks, and add them to the pan, followed by the peeled and crushed garlic cloves.
• Add the flour to the pan, stir to coat everything so no lumps remain.
• Add the ale, vegetable stock, tomato purée, brown sugar, cider vinegar and thyme. Bring to the boil then reduce to a gentle simmer. Wash the pearl barley well, drain and add to the pan.
• Peel the carrots, slice vertically then into large chunks. Cut the potatoes into quarters or thick slices. Add them to the pan, bring it back to the boil and then reduce again to a simmer.

To finish on the hob / stove:

• Simmer the stew for 30-35 minutes until the pearl barley is tender, and the carrots and potatoes are just cooked through.

  If the gravy becomes too thick, add a splash or water, or put a lid on for the remaining cooking time.

  If the gravy is too thin at the end of cooking time, turn up the heat and cook for a few extra minutes until it has reduced and thickened.

To finish in a slow cooker:

• Tip the stew into a slow cooker, and cook on high for 3-4 hours or on low for 5-6 hours, until the pearl barley, carrots and potatoes are tender.