Tuna: In medium bowl, combine first 7 ingredients. Add remaining ingredients and toss lightly to combine. Spoon evenly into individual baking dishes. Sprinkle topping over tuna mixture. Run under broiler, six inches from heat, until crumb mixture browns (about 5 minutes). Garnish with parsley and lemon slices and serve immediately.
Topping: Toss all ingredients together until well mixed.
