Preheat the oven to 200C/180C fan/Gas 6. Put the potato wedges and onion wedges in a large roasting tin. Drizzle with the oil, sprinkle with thyme, salt and pepper, and toss to coat.
Roast for 15 minutes. Remove from the oven and turn everything over.
Nestle the sausages in amongst the potatoes and onions. Return to the oven for 20 minutes until the sausages are golden and the potatoes are crispy.
Mix the honey and mustard together. Brush or drizzle over the sausages in the last 5 minutes of cooking.
Serve straight from the tray with a green vegetable or baked beans on the side.