Heat oven to 220C/fan 200C/gas 7.
Place the potatoes in a roasting tin,
then rub with 1 tbsp oil and a sprinkling
of salt. Roast for 20 mins, then add
the onion wedges to the tin, giving
everything a good shake. Roast for
20 mins more until the potatoes have
turned a deep golden brown and the
onions have caramelised and softened.
Leave to cool slightly.
Heat a non-stick frying pan. Dry-fry
the bacon until crisp. Add the sliced
mushrooms, then fry for 5 mins more
until they have softened.
Meanwhile, make the dressing. Whisk
the mustard, vinegar and remaining
1 tbsp oil with a splash of water. Place
potatoes, onions, bacon and mushrooms
in a large bowl with the salad leaves, pour
over the dressing, then toss well. Divide
between 4 plates, then crumble over the