Separate egg yolks and whites. Set yolks aside for Pineapple-Lime Curd. For meringue, let whites stand at room temperature 30 minutes. Preheat oven to 300 degrees F. Line a baking sheet with parchment paper. In large mixing bowl beat whites, vanilla, and cream of tartar with electric mixer on medium-high until soft peaks form. Beating on high, add granulated sugar, 1 Tbsp. at a time, until stiff peaks form (about 8 minutes total).
Spread meringue on prepared baking sheet to make large oval, (about 13x9 inches), building up edges slightly to form a "nest." Bake 35 minutes. Turn oven off; let stand 1 hour. Carefully lift meringue off paper and transfer to serving platter.
Meanwhile, prepare Pineapple-Lime Curd.
In 12-inch skillet, cook pineapple slices in the 2 tablespoons hot butter for 8 minutes or until browned, turning once. Sprinkle with brown sugar. Cook, uncovered, for 1 to 2 minutes more or until sugar is dissolved.
To assemble, fill meringue nest with Pineapple-Lime Curd and top with seared pineapple slices. Drizzle with juice from seared pineapple. Serve at once topping with key limes and mint. Makes 10 servings.
In medium saucepan, combine sugar and cornstarch. Stir in lime juice, pineapple juice concentrate and water. Cook and stir over medium heat until thickened and bubbly. In medium bowl whisk together reserved egg yolks from meringue until smooth. Gradually whisk half of the hot mixture into yolks. Return yolk-juice mixture to saucepan. Cook and stir until mixture thickens and comes to a gently boil. Cook and stir 2 minutes more. Remove from heat; stir in butter until melted. Transfer to bowl. Cover and refrigerate.