Braised Beef Tips in a Rich Mushroom-Thyme Gravy with Celery Root Mash and Haricots Verts

Pat 1.5 lbs beef sirloin tips dry with paper towels and cut into 1.5-inch pieces. Season generously with 1.5 tsp kosher salt and 0.5 tsp black pepper.

Heat 2 tbsp vegetable oil in a large Dutch oven or heavy-bottomed pot over medium-high heat until shimmering. Working in batches to avoid crowding, sear beef tips for 3-4 minutes per side until deeply browned. Transfer to a plate and set aside.

Reduce heat to medium and add 12 oz sliced cremini mushrooms to the same pot. Cook for 6-7 minutes, stirring occasionally, until mushrooms release their moisture and begin to brown.

Add 1 diced medium yellow onion to the mushrooms and cook for 4-5 minutes until softened. Add 4 minced garlic cloves and 2 tbsp tomato paste, stirring constantly for 1 minute until fragrant.

Sprinkle 3 tbsp all-purpose flour over the vegetables and stir well to coat, cooking for 2 minutes to remove raw flour taste.

Pour in 1 cup dry red wine, scraping up any browned bits from the bottom of the pot. Allow to simmer for 3-4 minutes until reduced by half.

Add 2 cups beef stock, 4 fresh thyme sprigs, 1 bay leaf, and 1 tbsp Worcestershire sauce. Return the seared beef tips and any accumulated juices to the pot. Bring to a boil, then reduce heat to low.

Cover and simmer gently for 60 minutes, stirring occasionally, until beef is fork-tender and gravy has thickened. Season with remaining 0.5 tsp kosher salt and 0.5 tsp black pepper to taste.

While beef braises, prepare celery root mash: Place 2 lbs peeled and cubed celery root and 1 peeled and cubed medium russet potato in a large pot. Cover with cold salted water and bring to a boil.

Cook celery root and potato for 20-25 minutes until completely tender when pierced with a fork. Drain well and return to the pot.

Add 3 tbsp unsalted butter and 1/4 cup heavy cream to the celery root mixture. Mash until smooth and creamy using a potato masher or ricer. Season with salt to taste and keep warm.

About 10 minutes before serving, bring a large pot of salted water to a boil. Add 12 oz trimmed haricots verts and blanch for 3-4 minutes until crisp-tender and bright green.

Drain haricots verts and immediately toss with 1 tbsp unsalted butter and 1 tsp lemon juice. Season with salt and pepper to taste.

Remove thyme sprigs and bay leaf from the braised beef. Taste and adjust seasoning as needed.

To serve, spoon celery root mash onto plates, top with braised beef tips and mushroom-thyme gravy, and arrange haricots verts alongside.