Preheat oven to 375°F.
Place the water, butter, salt and sugar in a medium-sized saucepan and heat over medium heat while stirring occasionally. (Make sure the salt and sugar dissolve completely in the warm water, and the butter melts BEFORE the water comes to a boil).
As soon as the water comes to a boil (with a few bubbles breaking through the surface), move the pot away from the stove and add all of the sifted flour into the boiling liquid. Using a wooden spoon or a heat-proof silicone spatula, stir the mixture vigorously to allow the flour to absorb all the water and form a ball of dough, and remove any flour clumps in the dough.
After about 45 - 60 seconds of mixing, return the saucepan to the stove (with medium heat), and let the dough cook for a further 2 - 3 minutes while stirring and mixing. Do this until you see a film of dough forming on the bottom of your saucepan (please note that this only occurs with stainless steel saucepans, not in non-stick saucepans).
Remove the saucepan from the heat and transfer the dough into a large mixing bowl. Mix the dough gently, for about 2 - 3 minutes, to release the steam and to let it cool down (lower than 160°F). Alternatively, you can flatten the dough along the wall of the mixing bowl and let it cool down for a few minutes.
Crack all the eggs into a jug and whisk well to combine.
When the dough has cooled down, mix in the vanilla (I don’t use vanilla, but you can if you like). Next add the eggs in 5 - 6 additions, mixing each addition well into the dough before adding more. You can use a stand mixer or a spatula to mix in the eggs. Stop adding eggs when the dough starts to get a sheen, and looks glossy. Please read the post for more details. Then check for the right dough consistency with the choux pastry test (detailed in the post).
Place the dough in a 16 inch pastry bag and secure the bag opening, and set it aside until you get the baking trays ready. Line a baking tray with a silpat mat. Also have a bowl of water and a bowl of confectioner’s sugar with a small mesh strainer ready as well.
Fit a different pastry bag with a ½ inch French star tip. Then snip the end off of the choux pastry bag from the previous step, and place that in the bag with the French star tip.
Hold the pastry bag at a 45° angle, with the French star tip touching the silpat. Pipe 8 - 10 eclairs (4 - 5 inches in length) on the silpat lined baking tray. When piping, make sure the ends are a little larger than the middle portion of the eclairs. Twist the piping tip at the end so that you end with a slightly pointed/jagged end.
Dip your finger in water and pat the ends of the eclairs to flatten the pointed ends. Sift some confectioner’s sugar over the eclairs.
Place the baking tray in the middle rack of your oven, and set the timer to 25 minutes. After 25 minutes, check if the eclairs have turned golden brown. If they have, then open the oven door and quickly prick each of the eclairs with a sharp toothpick or skewer on one end.
Close the oven door and let the eclairs bake for a further 5 - 10 minutes until they turn a darker golden color. You want the eclairs to be baked a little longer so that they hold their shape better.
Remove them from the oven, and immediately prick the eclair cases on the other end. Let them cool down for about 10 minutes on the baking tray and then transfer them onto a wire rack.
Pipe more eclairs on the second silpat lined baking tray and bake. Repeat until you have used up all of your choux pastry.
Once the eclairs have cooled down, they are ready to be filled. If you’re filling them later, place the unfilled shells in an air-tight container and freeze for later.