Preheat the oven to 190°C. Boil the potato, carrot and parsnip slices for 3–4 minutes or until just tender. Drain well, then set aside.
Coat a non-stick frying pan with cooking spray. Cook the sausages over a medium heat for 10 minutes, turning occasionally. Remove the sausages from the pan and set aside.
Add the onion to the pan and sauté for 5 minutes, stirring, until golden. Stir in the paprika and flour, then gradually mix in the stock. Bring to the boil, stirring, then reduce the heat to medium and simmer until thickened and smooth. Stir in the Worcestershire sauce, 2 tsp of the mustard and the sugar. Add pepper to taste. Add the beans. Cut the sausages into thick slices and stir into the sauce. Bring to the boil.
Spoon the sausage and bean mixture into a 1.5 litre shallow baking dish. Arrange the sliced root vegetables over the top, starting in the centre and working out in overlapping rings, covering the entire surface. Mix the remaining mustard with the melted margarine and brush over the top.
Bake for 30–35 minutes or until the sauce is bubbling and the vegetable topping is golden brown. Serve hot.
Some more ideas…
*For a vegetarian hotpot, use meat-free sausages and vegetable stock, preferably homemade. Replace the Worcestershire sauce with a mild chilli sauce. *Make a mash topping: Cut the potatoes, carrot and parsnip into chunks and cook in boiling water for 15–20 minutes. Drain well, then mash with ¾ cup (200 g) reduced-fat ricotta cheese and add pepper to taste. Spread over the sausage and bean mixture, then dot with 1½ tbsp margarine and sprinkle with a little paprika. Bake as in the main recipe.
*Both parsnips and potatoes provide useful amounts of potassium. Parsnips also contain useful quantities of some of the B vitamins, particularly folate and B1. *Since the sausages and stock are quite salty, there's no need to add extra salt.