We like it rare to med-rare
To liberal amount of dijon, add minced garlic, splash of red wine vinegar, S&P,dried thyme. a few cracked bay leaves, rub in and coat whole roast.let sit 1 day. google or do 52 Search for temp and timing.
What's with the no-sear thing? It's a key part if the process.
Plenty of recipes on the internet, or this site. But remember, that bright yellow stuff called Fr-nch's is not mustard. Buy a nice Dijon, smooth or grainy. Smooth will be hotter than grainy. Consider mixing two different mustards together...grainy for the texture and a hot English Coleman for heat.