Heat your oven to 200°C/Fan 180°C/Gas 6. Scrub and halve the potatoes. Tumble them into a large roasting tin, toss with 1 tbsp oil and a good pinch of salt and pepper. Roast for 15 mins.
While the potatoes roast, slice the tomatoes into wedges. Trim the courgette and slice it into chunky batons. Tuck the tomatoes and courgette around the potatoes in the roasting tin and return to the oven for a further 20 mins.
While the veg roasts, tip the spinach into a food processor. Peel and grate in the garlic clove. Grate in the lemon zest and squeeze in the juice. Trim the roots off the spring onions, roughly chop them and add to the processor with 1 tbsp oil and a sprinkle of salt and pepper. Blend till everything comes together into a pesto. No food processor? See our tip at the end.
When the potatoes are almost cooked, pour 1 tbsp oil into a large frying pan and warm over a high heat for 2 mins. Carefully add the diced rump steak and a pinch of salt and pepper. Fry for 3-4 mins, turning once or twice, till the pieces are golden on all sides.
Arrange the potatoes, tomatoes, courgette and rocket leaves on 2 plates and top with the rump steak. Finish with generous dollops of the spinach pesto and serve.