Reverse Sear Rib Roast (Prime Rib)

Lunch | British

Prep time: 24 min Cook time: 5 min Servings: 8

Rib eye is my favourite cut of beef to cook around the holidays. It has so much flavour, a great way to cook beef and it feeds a lot of people. It is a more expensive cut so nice to save it for a special occasion.

The reverse sear is the most reliable method I know for cooking a large cut of beef. You start low and slow, roasting the rib roast at 95°C until the centre reaches 48°C, then pull it from the oven and let it rest at room temperature for 1 to 2 hours. The long rest allows the proteins to relax and the juices to redistribute evenly throughout the meat. Then a final blast at 230°C for 15 minutes forms a deep, golden-brown crust across the outside. The result is edge-to-edge even cooking from the centre to just under the bark, which is very difficult to achieve with a traditional high-to-low roast on a large cut.

If you have the time, the overnight dry brine is worth doing. Salting the beef uncovered in the fridge for 12 to 24 hours draws moisture to the surface and then reabsorbs it back into the meat, seasoning the beef deeper and leaving the exterior dry and tacky. That tacky surface is what helps the mustard paste adhere and what gives you a better crust at the final high-heat stage. The paste itself is dijon mustard, garlic, rosemary and olive oil: it adds a savoury, herbed bark to the outside of the roast that pairs well with the richness of the beef. A probe thermometer is non-negotiable here. The cooking time is approximate because every roast is a different shape and weight, and temperature is the only reliable indicator of doneness.

Ingredient Notes

3-point beef rib roast: A rib roast is a section of the beef rib primal, sold bone-in. A “3-point” roast refers to a 3-bone section, which at approximately 3kg is the right size for 6 to 8 people. The rib section is one of the most well-marbled parts of the animal, with good fat distribution through the meat and a generous fat cap on top that bastes the beef from the outside during the roast. Ask your butcher for a 3-point rib roast and have them tie it with twine, which helps the roast hold its shape during the high-heat sear at the end. The cut is sometimes labelled as “standing rib roast” or “prime rib” depending on the butcher.

Sea salt (dry brine): The dry brine here is simply salt applied generously to the outside of the beef, left uncovered on a wire rack in the fridge overnight. The salt draws moisture to the surface through osmosis, where it dissolves and forms a concentrated brine. This is then slowly reabsorbed into the meat over several hours, seasoning it more deeply than surface seasoning alone would achieve. The uncovered rest in the fridge also dries out the surface, which sets up a better crust when the beef hits the high heat at the end. If you don’t have time to dry brine overnight, season well just before cooking: you’ll still get a good result, just with less depth of seasoning.

Dijon mustard: In this recipe, dijon mustard acts as a binder for the herb crust as well as a flavour element. It coats the outside of the beef and gives the garlic and rosemary something to grip onto during the roast. Dijon has a sharp, clean heat and a slight acidity that cuts through the richness of the rib roast without overwhelming it. During the high-heat sear at the end, the mustard sugars caramelise and contribute to the deep brown crust. Wholegrain mustard works as an alternative and will give a slightly coarser bark. Avoid regular yellow mustard: it’s too sweet and won’t give the same result.

Equipment

Chopping board
Chef’s knife
Probe thermometer
Wire rack
Large baking tray
Small bowl
Roasting pan or oven-safe tray
Carving board

Ingredients

3 point beef rib roast, approximately 3kg (6.6 lbs)
sea salt and freshly cracked pepper
2 tbsp dijon mustard
3 cloves garlic, finely grated
2 sprigs rosemary, leaves picked and chopped
60ml (¼ cup) olive oil

Directions

Overnight brine (the day before)
Season the beef generously all over with salt. Place on a wire rack over a tray and refrigerate overnight ideally, uncovered to dry brine.
Prep the beef
Combine the dijon mustard, garlic, rosemary and oil in a small bowl. Season with salt and pepper and mix well.
Spread the mustard mixture onto the beef, starting with the underneath, then the sides, then turn it over and rub all over the top of the beef.
Place a thermometer probe into the centre of the beef if you have one. If you don’t, you’ll just need to check the beef temp throughout the cook.
Roast the beef
Preheat the oven to 95°C (203°F). Roast the beef for approximately 3 - 4 hours*, until the internal temperature reaches 48°C. (46 for rare, 52/53 for medium)
Set the beef aside to rest at room temperature for 1 - 2 hours.
Finish and serve
Increase the oven temperature to 230°C (446°F).
Return the beef to the oven for 15 minutes, or until the outside is golden brown.
Transfer the beef to a carving board and slice. Serve with your favourite festive side dishes.

Recipe notes

Chef Tips

Use a probe thermometer, not a timer

The 3 to 4 hour low-oven time is a guide only. Every roast is different depending on shape, thickness and starting temperature, and the only reliable way to know when it’s ready is by internal temperature. Insert the probe into the thickest part of the meat, away from the bone. Pull the roast at 48°C for medium-rare, 46°C if you prefer rare, or 52°C for medium. The beef will not rise significantly in the low oven, but the 230°C blast at the end will add a few degrees, so pulling at your target temp is correct here.

Don’t skip the rest

The 1 to 2 hour rest is a critical part of the reverse sear method, not optional. After the low oven, the proteins are relaxed and the juices are evenly distributed. The rest keeps it that way. If you skip the rest and go straight to the high-heat sear, the juices will run out when you carve. If you need to hold the beef for longer than 2 hours before the final sear, keep it in an insulated box or esky to maintain the temperature and prevent it cooling down too far.

Storage

Store leftover beef in an airtight container in the fridge for up to 4 days. Reheat slices gently in the oven at a low temperature (around 120°C) until the internal temperature reaches 40°C, which will warm through without overcooking. Cold leftover rib roast also works well sliced thinly for sandwiches or sliced over a salad.

Serving ideas

This roast will go great with some beef fat roasted potatoes, a green side salad,

steamed greens or grilled vegetables.

FAQs

Do I have to dry brine overnight? No, but it does make a noticeable difference to the depth of seasoning and the quality of the crust. If you’re short on time, season generously with salt just before applying the mustard paste and you’ll still get a good result. Even a few hours uncovered in the fridge helps more than no brine at all.

Can I do the reverse sear on a BBQ? Yes. Set up your BBQ for indirect heat at around 95°C and follow the same method. The final sear can be done over direct high heat on the grill grates rather than returning to a hot oven, which gives a slightly smokier crust. Use a probe thermometer either way: the same temperature targets apply.

What if I don’t have a probe thermometer? A probe thermometer is strongly recommended for this recipe: the reverse sear relies on hitting a precise internal temperature, and the cooking time varies too much to rely on a timer. Probe thermometers are available from kitchen stores, hardware stores and BBQ specialists and are a worthwhile investment for any large cut of meat. A basic instant-read thermometer will also work in place of a leave-in probe.