Instructions for eclairs:
Heat oven to 200°C. Line a large baking sheet with baking paper.
In a medium sized pot with a thick bottom, mix together water, oil, salt and sugar and heat to the boil. Remove from heat and stir in flour with wooden spoon. Stir quickly and vigorously to prevent lumping. Leave mixture a few minutes to cool.
Slowly add eggs, 2–3 times, stirring vigorously after each addition, until the mixture is smooth, thick and shiny. Fill a pastry bag with a round tip with the mixture, and pipe into 5–6 cm long strips onto the baking sheet, drawing ends upwards. Leave enough space between strips, as the pastry will rise during baking. Lightly press raised tips down with a moist finger, to prevent them from burning.
Bake for 35–40 minutes, until the pastry is evenly golden. Remove from oven and allow to cool completely before filling with cream.
Instructions for cream:
Add milk to a thick bottomed pot and scrape in vanilla seeds from bean. Heat to the boil and remove from heat. As the milk is heating, mix egg yolks, sugar, salt and corn starch well in a bowl. Add 4–5 tablespoons of the heated milk.
Pour the egg mixture into the heated milk, and stir vigorously with a wooden spoon over light heat until the cream thickens. Stir well to keep cream from sticking or burning on the bottom of the pan. Once thickened, remove from heat, transfer to a bowl and cover with plastic wrap. Chill.
Assembly and decoration:
Cut cooled eclairs in half horizontally lengthwise with a serrated knife. The eclairs will be hollow in the middle. Using a pastry bag with a star tip, pipe cream onto the bottom half of the pastry so that the cream completely fills the empty space and reaches a height of about 1.5 cm above the pastry surface. Cover with the top half of the pastry.
Decorate the top half with chocolate glaze made from melted chocolate. Alternatively, you can decorate them with icing sugar or a sugar glaze. Once prepared, keep eclairs in the refrigerator until serving.