Preheat oven to 220°C (200°C fan) / Gas Mark 7.
Toss onions, peppers, garlic, thyme, potatoes, and sausages with olive oil. Spread on roasting tin, season.
Roast 30–35 minutes, flipping sausages and tossing vegetables halfway.
Add white wine, roast another 20 minutes until sausages browned and potatoes tender.
Serve hot with mustard on the side.
