1. Preheat oven to 325°.
2. To prepare meringues, line a baking sheet with parchment paper. Draw 6 (3-inch) circles on paper. Turn paper over; secure paper with masking tape onto baking sheet.
3. Place egg whites and salt in a large bowl; beat with a mixer at medium speed until foamy. Increase mixer speed to medium-high. Gradually add sugar, 1 tablespoon at a time, beating until stiff peaks form. Add 1 1/2 teaspoons cornstarch, 1/2 teaspoon lemon rind, and 1 1/2 teaspoons lemon juice; beat 1 minute or until the mixture is well combined.
4. Divide egg white mixture among 6 drawn circles on parchment paper. Shape meringues into nests with 1-inch sides using the back of a spoon. Place baking sheet in oven; immediately reduce oven temperature to 225°. Bake meringues at 225° for 1 hour or until dry to the touch. Turn oven off (leave pan in oven); partially open oven door. Cool meringues in oven 1 hour. Remove pan from oven; carefully remove meringues from paper. (Meringues will be crisp on the outside and soft on the inside.)
5. To prepare curd, combine granulated sugar and next 5 ingredients (through yolks) in a medium saucepan; bring to a boil, stirring constantly. Reduce heat, and cook 1 minute or until thick and bubbly, stirring constantly. Remove pan from heat; add butter, stirring until butter melts. Pour mixture through a sieve into a bowl. Place plastic wrap on surface of curd, and chill.
6. Peel and section tangerines; discard membranes. Spoon about 2 1/2 tablespoons curd into each meringue. Top each meringue with about 3 tangerine sections.