Topside is a lean roasting joint from the back of the animal. It is not ribeye and it is not brisket. Roast it like a steak that happens to weigh a kilo: brown, timed heat, and a rest long enough that you can slice it thin without a puddle. Topside Joint 1kg is that 1kg joint, enough for four if you carve properly and have gravy. It lives in topside and Sunday roast.
Oven times for 1kg
Bring it out of the fridge 30 minutes before. Season, brown all sides in a pan, 2 minutes a face. Onto a small tin with an onion underneath, 180°C. For medium-rare topside, 20 minutes per 500g plus 20 minutes is too long and will take you to well done. A better rule on 1kg: 35 to 45 minutes total after browning, probing for 52–54°C in the centre for pink, 58°C for medium. Rest 15 to 20 minutes, loosely foiled. The rest is when a lean joint becomes edible; skip it and the juice is on the board. Slice thin, across the grain. Thick slabs of topside are why people say they “don’t like roast beef”.
Air fryer and leftovers
A 1kg topside will often fit in a large air fryer: 180°C for 35 to 40 minutes, turning once, still probe and rest. It will not have the same tin gravy; deglaze a pan with the juices. Leftover topside is the next-day sandwich cut. Cold, it should be pink in the middle if you roasted it right. Shop beef joints if you want a sirloin joint instead — Sirloin Joint 1kg is a more forgiving roast because of the fat cap. Large roasting joints is the shelf when 1kg is not enough table.
Gravy and what not to do
The onion and juices in the tin, a spoon of flour, stock, and a boil is gravy. Do not swamp a lean joint in a casserole lid-on for three hours and call it topside; that is a pot roast and you should have bought chuck. Do not cook it from frozen. Do not carve the minute it leaves the oven. A 1kg topside is a small Sunday, not a buffet. If you need to feed eight, buy a bigger joint rather than two tiny ones that will overcook on the outside while you wait for the centres.
Brown, probe, rest 20 minutes, slice thin. That is a 1kg topside, and it is a proper roast if you treat it as lean beef rather than as a cheap stand-in for rib.