For the filling: Heat the milk, vanilla pod and scraped seeds in a medium saucepan over medium heat. When it boils, remove from the heat and let steep for 5 minutes. Whisk together the egg yolks and sugar in a medium bowl until light and fluffy. Whisk in the cornstarch until smooth.
Remove the vanilla pod from the milk mixture and discard. Carefully whisk 1/2 cup of the hot milk mixture into the egg yolks until incorporated, then whisk the egg yolk mixture back into the saucepan. Cook over medium-high heat, whisking constantly, until the mixture is gently bubbling and thickened and coats the back of a spoon, about 5 minutes. Remove from the heat and whisk in the butter. Transfer the mixture to a glass or metal bowl and let cool slightly, about 10 minutes. Cover with plastic wrap, pressing the plastic directly against the surface to prevent a skin from forming. Chill at least 2 hours or until ready to serve.
For the pastry: Preheat the oven to 425 degrees F. Line a sheet pan with parchment paper. Combine 1 cup water, the butter, sugar and salt in a medium saucepan and bring to a boil over medium-high heat. When the mixture boils, immediately add all the flour at once and stir with a wooden spoon until it is fully incorporated and smooth, 1 minute. Continue to cook, stirring constantly, until the dough pulls away from the sides of the pan, about 30 seconds more. Scrape the mixture into a large bowl. Using an electric mixer on medium speed add the eggs 1 egg at a time, mixing well after each addition, until they are completely incorporated and the mixture is thick and smooth.
Transfer the mixture to a pastry bag fitted with a medium round tip. Pipe 2-inch lengths of dough onto the prepared baking sheet leaving about 1/2 inch between each. To make smooth eclairs, dip your finger in water and smooth out any bumps or points in the dough.
Bake for 20 minutes, then reduce the heat to 375 degrees F and bake until the eclair shells are puffed up and golden brown, about 30 minutes more. Place the eclairs on a wire rack and let cool completely on the baking sheet.
Transfer the chilled pastry cream to a pastry bag fitted with small plain tip. Use the tip to gently poke a hole into one end of each eclair shell. Pipe the custard into the eclairs until they are just filled (do not overfill). Alternatively, you may split each eclair open with a knife so that it opens like a book and spoon in the filling.
For the glaze: Place 1 cup of confectioners' sugar in each of 3 medium bowls. Whisk the orange juice concentrate and water in to one, the cranberry-raspberry juice into one and the Concord grape juice and water in to one, mixing until smooth. Dip the top of each filled eclair into a glaze, letting the excess drip off before turning over and placing on a platter. Let the eclairs rest until the glaze dries and is shiny, 30 minutes.
When measuring flour, we spoon it into a dry measuring cup and level off the excess. (Scooping directly from the bag compacts the flour, resulting in dry baked goods.)
Copyright 2016 Television Food Network, G.P. All rights reserved.