One-pot beer-braised sausages with warm potato salad

Ingredients

• 1/4 cup olive oil
• 2 onions, sliced
• 1 tablespoon sugar
• 1 tablespoon red wine vinegar
• 6 good-quality Italian pork sausages, blanched (see recipe tip)
• 4 spring onions, white part halved lengthways, tops sliced, reserved
• 4 garlic cloves, crushed
• 500 gram small new potatoes, halved lengthways
• 1 tablespoon mustard seeds
• 1 cup pale ale
• 200 gram green beans, trimmed
• 1/4 cup thickened cream
• 1/2 cup flat-leaf parsley, finely chopped