Bring 1-1/2 cups water to a boil in a medium-size saucepan. Add rice. Cover tightly, reduce heat to low; simmer 45 minutes.

Meanwhile, in a medium-size bowl, stir together the mayonnaise, mustard and egg yolk. Set aside.

Add broccoli florets, scallion and tarragon to wild rice and cook an additional 10 minutes or until rice is tender and water is absorbed. Remove from heat; cool about 10 minutes.

Transfer rice mixture along with grape tomatoes to bowl with mayonnaise mixture. Stir until evenly blended.

Heat oven to 400 degrees F. Coat a 13 x 9 x 2-inch baking dish with nonstick cooking spray. Place one of the flounder fillets skinned-side-up in prepared dish. Spoon a scant 2/3 cup rice mixture onto one half of the fillet, then fold over other half to cover. Repeat using remaining flounder fillets and rice filling. Sprinkle with paprika, salt and pepper; top each with two slices of lemon. Add wine or water to pan; transfer to oven.

Bake at 400 degrees F. for 20 minutes, until fish is solid white and flakes easily with a fork (filling should register 160 F on an instant-read thermometer). Remove to plates with a large spatula; serve with baby carrots.