Combine first 9 ingredients in a medium bowl; stir with a whisk.
Heat a Dutch oven over high heat until hot; add oil. Add beef; cook 4 minutes or until browned on all sides, stirring occasionally.
Reduce heat to medium-high; add fennel, onion, and mushrooms. Cook 5 minutes, stirring occasionally.
Add broth mixture; bring to a boil. Cover, reduce heat, and simmer 1 1/2 hours or until beef is tender.
Combine flour and water in a small bowl; stir with a whisk until smooth. Stir flour mixture into beef mixture. Add corn. Cover and simmer 8 minutes. Garnish with fennel sprigs, if desired.