Put the water to boil along with the oil. Pour the flour in all at once, remove the container from the heat and stir vigorously until you get a smooth mixture. Allow the mixture to cool, then add the eggs one at a time, while stirring constantly.
Put this mixture for the éclairs in a pastry bag and form small shapes on foil or baking paper. Preheat the oven to 320°F (160 °C) and place the mini éclairs to bake until browned (without opening the oven).
Once they are ready, do not rush to take them out but leave them to cool in a slightly open and turned off oven.
To prepare the cream, put the milk and sugar to boil. Beat the eggs with a mixer, add the flour and 1/5 cup (60 ml) of milk or water until you get a thick blend. Pour this blend in a thin trickle into the hot milk, stir vigorously and be careful not to get lumps in the mixture.
Fill the mini éclairs with the cream using the extended nozzle of an icing piping syringe. Finally, sprinkle with powdered sugar.