Cook Time: 4 hours

Ingredients:

Jus:
2 Tbs Unsalted Butter
1 Large Sweet Onion, Thinly Sliced
2 Tbs Sugar
1 Garlic Clove, Crushed
2 Sprigs of Thyme and Bay Leaves
1/3 Cup Port
5 1/2 Cups Beef Broth
1 Tbs Sherry Vinegar
1 Tbs Worcestershire Sauc
Kosher Salt and Pepper to Taste

Roast Beef:
2 Tbs Canola Oil
2 Lbs Trimmed Beef Tenderloin, Room Temp
Kosher Salt and Pepper
4 Tbs Unsalted Butter
4 Garlic Cloves, Crushed
2 Thyme Sprigs
1/2 Cup Beef Broth

Aioli:
3 Large Egg Yolks
2 Tbs Champagne or White Wine Vinegar
Kosher Salt and Pepper
1 Cup Canola Oil
3 Tbs Drained Horseradish

Sandwiches:
1 Small Shallot, Minced
1 Garlic Clove, Minced
4 Tbs Unsalted Butter
1/2 lb Baby Spinach
Kosher Salt
Baguette
3/4 Lb Gruyere Cheese, Shredded

Directions:
1) Making The Jus. In a Saucepan, melt the butter. Add the onion and cook over moderate heat, stirring until starting to brown, 10 Minutes. Add the sugar, garlic, thyme, and bay leaves and cook over moderately low heat, stirring until the onion is deep golden, about 20 minutes. Add the port and simmer until nearly absorbed, ~2 minutes, Add the broth, vinegar, and Worcestershire sauce and simmer over moderate heat until reduced to 2 cups, ~30 minutes. Strain the jus into a saucepan and season with salt and pepper.

2) Roast The Beef.  Preheat the oven to 325 F. Heat the oil in an ovenproof skillet. Season the meat with salt and pepper and sear until browned all over. Add butter, garlic and thyme to skillet, baste the meat for 1 minute. Transfer to the oven and roast for ~30 minutes, basting every 5 minutes. Cook until and instant read thermometer reads 128 F; transfer meat to a rack and let rest for 20 minutes. Add broth to pan and scrape up any brown bits. Boil until reduced to half, strain into jus and skim off fat.

3) Make The Aioli. In a food processor, blend the egg yolks, vinegar, and a large pinch of salt and pepper for ~90 seconds. With the machine on add the oil in a slow, steady stream. Transfer to a bowl, stir in the horseradish and season with salt and pepper.

4) Make The Sandwich. In a skillet, cook the shallot and garlic in 1 tablespoon of butter, until softened. Add the spinach and season with salt. Cook, tossing, until just wilted; transfer to paper towels to drain.

5) Preheat the broiler. Thinly slice the beef. Arrange the baguettes on baking sheet and spread with aioli. Spoon spinach over bottom halves of sandwiches and layer meat on top halves, sprinkle with cheese. Broil until cheese melts.

6) Turn the oven to 425 F. Reheat the jus. Close the sandwiches, brush with the remaining melted butter and weigh down with a baking sheet and heavy skillet. Bake for 10 minutes; remove the weighted baking sheet and bake for 5 minutes. Serve with the jus.