Preheat oven to 200 °C or 180 °C fan bake. Bring a large steamer pot of hot tap water to a boil. Spray a baking dish with oil spray.
Cook sausages
Peel and slice 1 brown onion in half, then finely slice. Heat 1 tbsp olive oil in a large frypan over medium-high heat. Add the onion to the pan and cook for 1 minute or until starting to soften. Add 600 g beef sausages and cook, turning occasionally, for a further 4 minutes or until browned. Remove from heat and set aside.
Make gravy
Add 1 tbsp cornflour to a small jug or bowl. Stir in 30 ml or 2 tbsp from the 1 cup beef stock to make a smooth paste, then stir in 1 tbsp curry powder and the remaining beef stock.
Start bake
Half 2 carrot and 2 zucchini lengthways, then thinly slice on an angle. Cut 1 broccoli into small florets. Transfer sausages and onion to the baking dish. Add the courgettes, carrots, broccoli and 1 cup frozen peas. Stir to combine then pour the curry gravy over the top. Season with salt and pepper.
Finish bake
Bake for 10 minutes, then gently stir the vegetables in the curry gravy. Return to the oven and cook further 5-10 minutes or until sausages are cooked through and the vegetables are tender.
Make mash
Meanwhile, peel and dice 800 g potatoes. Cook in the steamer pot of boiling water for 12-15 minutes, or until very tender. Drain the pot then transfer the potatoes to the bottom pot with ¼ cup milk, 1 tbsp olive oil and ½ tsp onion powder. Mash until smooth and season to taste with salt and pepper.
To serve
Divide the curried sausage and vegetable bake between plates and serve with the potato mash on the side.