A real prime rib is a beautiful thing, and it is priced like one. This is the roast I make when I want that same moment at the table with a cut that is a lot kinder to the wallet. A beef top sirloin roast goes into a sous vide bath at 133°F for 8 hours, gets a hard, fast sear on the Blackstone, and lands on the plate next to crispy smashed baby gold potatoes.
Call it a poor man’s prime rib. The sous vide does the heavy lifting: it keeps the roast so tender, and every bite is cooked perfectly.
At a glance
| Cut | Beef top sirloin roast |
| Prep | Three wraps of butcher twine with a fresh rosemary sprig, then the final rub |
| Rub | Coarse pepper, kosher salt, paprika, and my garlic-herb blend |
| Bath | 133°F for 8 hours, vacuum sealed |
| Sear | Blackstone as hot as it gets, 60 to 90 seconds on every side and end, with melted butter |
| Potatoes | Baby golds, boiled whole 30 to 38 minutes in salted water, smashed, then roasted at 425°F for about 30 minutes |
1. Tie, season, and bag
Start with three wraps of butcher twine around the roast, with a fresh rosemary sprig worked in under the twine. Then comes the final rub: coarse pepper, kosher salt, paprika, and my blend of garlic and herbs, all over. Vacuum seal it.
2. Into the bath
Set the water bath to 133°F and let it go for 8 hours. That is the whole job. Walk away.
3. Out of the bath, pat it dry
This is the step I would not skip. When the roast comes out of the bag it is wet and pale, and that wet surface is what keeps a crust from forming. Pat it completely dry with paper towels before it goes anywhere near the griddle.
4. Sear it hard
Melt some butter and get the Blackstone as hot as it gets. Sear every side and both ends for 60 to 90 seconds each, and brush the melted butter on with the rosemary sprig while you go. The sprig makes a good little basting brush, and it adds a little rosemary flavor on the way.
Because the inside is already cooked, the sear is only there for the crust. That is why it can be quick and aggressive.
5. Smashed potatoes
Baby gold potatoes, boiled whole for 30 to 38 minutes. The water is always salted, every time. Move them to a cookie sheet and smash each one lightly with the bottom of a glass (or anything flat), just enough to flatten them a bit.
Drizzle with avocado oil and a splash of olive oil, then add salt, pepper, and the garlic-herb mix before they go in. Into a 425°F oven for about 30 minutes, until slightly crispy.
6. Slice and plate
Slice it and look at that color. Pink edge to edge, which is the sous vide payoff.
Tips
- Pat the roast dry after the bath. It matters more than anything else on the list.
- Get the griddle as hot as it goes. A short, hot sear keeps the inside exactly where the bath put it.
- Brush the butter on with the rosemary sprig during the sear.
- Salt the potato water.
- Smash gently. You are flattening, not mashing.
A note on low-temperature cooking
Cooking beef at 133°F for hours is a time-and-temperature job, so it deserves a little homework before you copy it. If you are new to sous vide, read up on how long beef needs to be held at a given temperature. The University of Nebraska beef report and Anova’s pasteurization guide are good places to start, and USDA FSIS publishes its own guidance too. Make sure your bath is actually holding the temperature you set.
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