Step 1

Generously season both sides of roast with salt and pepper. Sprinkle flour over the top until well coated, and pat it into the meat. Shake off any excess.

Step 2

Heat vegetable oil in a large skillet over medium-high heat until hot. Sear the roast on both sides for 5-6 minutes each, until well browned. Remove from the skillet and set aside.

Step 3

Reduce the heat to medium and stir in mushrooms and butter; cook for 3-4 minutes.

Step 4

Stir in onion; cook for 5 minutes, until onions are translucent and begin to brown. Add garlic, stir for about a minute.

Step 5

Stir in 1 1/2 tablespoons flour; cook and stir for about 1 minute. Add tomato paste, and cook for another minute.

Step 6

Slowly add chicken stock, stir to combine, and return to a simmer. Remove skillet from the heat.

Step 7

Place carrots and celery in the slow cooker. Place roast over the vegetables and pour in any accumulated juices. Add rosemary and thyme.

Step 8

Pour onion and mushroom mixture over the top of the roast. Cover slow cooker, turn to high and cook the roast for 5-6 hours, until the meat is fork tender.

Step 9

Skim off any fat from the surface and remove the bones. Season with salt and pepper to taste.