Cook:10 hrs to 11 hrs (low) or 5 to 5 1/2 hours (high)
Trim fat from meat. If necessary, cut meat to fit into a 5- to 6-quart slow cooker. Sprinkle meat with 1 teaspoon of the Greek seasoning; rub in with your fingers. Place meat in the cooker. Top with fennel wedges or celery and fennel seeds.
In a medium bowl, combine undrained tomatoes, broth, olives, salt, lemon peel, pepper, and the remaining 2 teaspoons Greek seasoning. Pour over brisket mixture in cooker.
Cover and cook on low-heat setting for 10 to 11 hours or on high-heat setting for 5 to 5 1/2 hours.
Remove meat from slow cooker, reserving cooking juices. Thinly slice meat. Arrange meat and vegetables on a serving platter. Cover meat and vegetables; keep warm. Pour cooking juices into a glass measuring cup; skim off fat.
For sauce, if necessary, add water to cooking juices to make 2 cups. Transfer to a small saucepan. In a small bowl, combine the 1/4 cup water and the flour; stir into mixture in saucepan. Cook and stir until thickened and bubbly. Cook and stir for 1 minute more. Serve sauce with meat and vegetables. If desired, serve with hot cooked noodles.