For the Dukkah Spice Blend, heat medium skillet on medium heat. Add nuts; cook and stir 2 to 3 minutes or until fragrant and toasted. Immediately pour out of hot pan to avoid over-toasting. Set aside. Toast coriander, sesame and cumin seeds in same skillet on medium heat 2 minutes or until fragrant and toasted. Immediately pour out of hot pan. Place 1/2 of the toasted nuts in clean coffee grinder. Process until finely ground and crumbly. (Do not allow mixture to become a paste.) Transfer to small bowl. Repeat with remaining nuts then seed mixture. Add pepper and salt to seed and nut mixture; mix until well blended. Store extra in an airtight container in cool, dry place up to 1 month.
Soak lentils in cold water 20 to 30 minutes. Drain. Bring 4 cups water to boil in medium saucepan. Add lentils; cook 5 minutes. Drain and rinse under cold water. Set aside. Trim tough bottom stems of Chinese broccoli. Coarsely chop stems and leaves. Set aside.
Moisten fish fillets lightly with water. Coat 1 side of each fillet generously with 2 teaspoons of the Dukkah Spice Blend. Heat 2 tablespoons of the oil in large nonstick skillet on medium heat. Add fish, spice blend-side down, cook 3 to 5 minutes per side or until golden brown and fish flakes easily with a fork. Remove fish to serving platter. Keep warm. Wipe skillet clean with paper towel.
Heat remaining 1 tablespoon oil in same skillet on medium heat. Add shallots; cook and stir 3 minutes or until softened. Add Chinese broccoli, lemon peel and mint; cook and stir 3 minutes. Add tomatoes, lentils, stock, lemon juice and salt; cook and stir 1 to 2 minutes or until most of liquid has been absorbed and Chinese broccoli is tender-crisp. Stir in 2 tablespoons of the remaining Dukkah.
To serve, spoon Chinese broccoli mixture onto each plate. Top with fish fillet. Serve with remaining 2 tablespoons Dukkah for sprinkling, if desired.