
This healthy steak roast dinner delivers all the comfort of a classic roast with lean fillet steak, crisp roasted vegetables, and a simple pan gravy. It's a balanced, flavorful meal that feels special enough for Sunday dinner but is easy enough for a weeknight.
Preheat the oven to 180C/160C fan/gas 4. Bring a large pan of water to a boil, add the sliced potatoes, and simmer for 5 minutes until just starting to soften. Drain well, reserving 125 ml of the cooking water.
Place the potatoes, carrots, red onions, and Brussels sprouts on a large nonstick baking tray. Drizzle with 2 tsp of the rapeseed oil, season with black pepper, and scatter over 1 tsp of the thyme. Toss to coat, then spread everything into a single layer. Roast for 30 minutes.
While the vegetables roast, stir together 1 tsp balsamic vinegar, the remaining 1/2 tsp oil, garlic, remaining 1 tsp thyme, and mustard powder. Rub this mixture all over the steak and set aside. In a small bowl, mix the remaining 1 tsp balsamic vinegar with the bouillon powder and 125 ml reserved potato water. After the vegetables have roasted for 30 minutes, turn them and return the tray to the oven for 15 more minutes, or until tender and caramelized.
Heat a small nonstick frying pan over medium-high heat. Remove excess marinade from the steak and cook for 2 to 3 minutes per side for medium-rare, or until done to your liking. Transfer to a board and rest for 5 minutes. Pour the remaining marinade and the bouillon mixture into the pan, simmer for 1 to 2 minutes until lightly thickened, then slice the steak and serve with the roasted vegetables and gravy.
For even browning, do not overcrowd the tray. If you cannot find fillet steak, sirloin works well too. Store leftovers in an airtight container in the fridge for up to 2 days and reheat gently to avoid overcooking the steak.