Crockpot Beef Stew

The original recipe came from the Allrecipes website. I've changed it slightly to account for our tastes.

Crockpot Beef Stew
6 potatoes, peeled and quartered
1 pound carrots, cut into 1-inch pieces
1 large onion, chopped
1 stalk celery, cut into 1-inch pieces
2 pounds lean beef stew meat, cut into 1-inch cubes
1/3 cup butter
1 tablespoon all-purpose flour
1 cup water
1 teaspoon salt
1/2 teaspoon dried thyme
1/8 teaspoon pepper
1 Tbsp beef boullion
Place potatoes, carrots, celery, and onion in a 5-qt. slow cooker. In a large skillet, brown beef in butter. Transfer beef to slow cooker with a slotted spoon.
Stir flour into the pan drippings until blended; cook and stir until browned. Gradually add water. Bring to a boil; cook and stir for 2 minutes or until thickened. Add salt, thyme, boullion, and pepper; pour over beef. Cover and cook on low for 8-9 hours or until meat and vegetables are tender.