Combine first 3 ingredients in a food processor, and process until minced. Combine the fennel mixture with beef, rice, bulgur, and oil. Grate tomato halves over mixture; discard skin. Sprinkle beef mixture with pepper and salt; stir to combine.
Rinse grape leaves under cold water; drain and pat dry with paper towels. Remove stems, and discard. Spoon 1 rounded tablespoon of beef mixture onto the center of each grape leaf. Bring 2 opposite points of leaf to center, and fold over filling. Beginning at 1 short side, roll up leaf tightly, jelly-roll fashion. Repeat procedure with remaining grape leaves.
Place stuffed grape leaves close together, seam sides down, in a Dutch oven coated with cooking spray. Add broth and juice; bring to a boil. Cover, reduce heat, and simmer for 30 minutes. Carefully remove dolmades from pan. Combine cornstarch and water. Stir cornstarch mixture into broth; bring to a boil; cook for 1 minute. Stir in dill. Serve with dolmades. Garnish with lemon wedges, if desired.