Beef — Bring to room temperature before cooking. Heat Weber Baby Q to high. Sear ~5 mins each side, adjust for desired doneness and thickness. Rest before slicing.
Potatoes — Steam 15–20 mins until tender. While hot, toss immediately with a splash of rice wine vinegar and dill. Then dress with the caper-lemon dressing. Finish with extra dill.
Cos — Halve vertically, wash and dry thoroughly. Dress with caper-lemon dressing, top with grated Parmesan. To grill: brush cut side with oil, grill cut-side down 2–3 mins until charred, then dress.
Dressing — Combine capers, lemon zest, lemon juice, chives, salt, pepper, and olive oil. This dresses both the potatoes and the cos.
Notes
Vinegar on the hot potatoes first, then the oil-based dressing — the vinegar opens them up, the oil seals in the flavour.
One dressing ties the whole plate together; individual garnishes (dill for potatoes, Parmesan for cos) keep each element distinct.
Fresh cos gives crisp contrast to the rich beef.
The acidity from vinegar and lemon cuts through the richness of the beef and cheese.
Great leftover use: tough or undercooked rump goes straight into the Instant Pot for pulled beef.