Preheat the oven to 200C (180C fan). Put the potatoes, onion and apple wedges in a large roasting tin. Drizzle with the olive oil and season with salt and pepper. Toss to coat.
Nestle the sausages among the vegetables. Roast for 25 minutes.
Mix the honey and mustard together in a small bowl.
Remove the tin from the oven. Brush the sausages and vegetables with the honey mustard glaze. Return to the oven for 10-15 minutes until the sausages are golden and the apples are caramelised at the edges.
Scatter with fresh herbs if using and serve straight from the tin.