The finished recipe. Rump Steak with Peppercorn Sauce and MashIngredients 1 to 6. 170 g Rump steak, fat trimmed (Weighed raw. The same piece weighed after cooking has lost water, so the protein per gram is higher and the total would come out about a quarter over.). 220 g Potato (Peeled weight. A floury variety mashes better. Raw, peeled weight.). 50 g Greek yogurt, 0% fat (Stirred into the pan off the heat so it does not split.). 5 g Butter. 100 g Beef stock (Made up from a cube or a pot.). 100 g Tenderstem broccoliIngredients 7 to 9. 1 tsp, coarsely crushed Black pepper. 1 tsp, about 6 g Dijon mustard. To taste SaltStep 1. Boil the potatoes in salted water until a knife slides in with no resistance, about twenty minutes. Drain, steam dry for a minute, then mash with the butter and season.Step 2. Steam or boil the tenderstem for three minutes while the potatoes finish.Step 3. Sear the salted steak in a hot dry pan for three minutes a side, then move it to a plate to rest.Step 4. Add the crushed pepper and stock to the same pan and boil hard until reduced by half, scraping up the brown bits. Take the pan off the heat, stir in the mustard and yogurt, and pour it over the sliced steak.