Wash the radicchio, remove the core and tear or cut the leaves into bite-sized pieces. Core the apple and cut it into thin wedges.
Cut the sirloin steak into thin strips and roughly chop the walnuts. Stir the olive oil, apple cider vinegar, mustard and salt together in a large bowl to make a dressing.
Heat olive oil in a frying pan and sear the steak strips briefly over a high heat. Then take the meat out of the pan and leave it to rest briefly.
Put the walnuts into the still-hot pan and toast them briefly until fragrant. That gives them more flavour and a bit more bite.
Toss the radicchio and apple wedges with the dressing until everything is lightly coated. Season the salad with a little more salt if needed.
Arrange the salad on plates and scatter the steak strips and toasted walnuts over it. Best served straight away.
Good to know
When it needs to be quick but should still taste like a proper meal, this dish is a good choice. Warm steak and a bittersweet salad simply work well together.
Swaps
Sirloin steak → chicken breast (plenty of protein). Walnuts → pecans (milder in flavour, also provide unsaturated fatty acids). Apple → pear (just as juicy, a little softer and often milder). Olive oil → avocado oil (heat-stable, with mainly unsaturated fatty acids).
Allergens
Contains walnuts (tree nuts) and mustard. For children, depending on their age, balance the bitter radicchio with more apple; in pregnancy, always cook the steak right through.
