Preheat the oven to 220°C (approximately 425°F).
In a bowl, mix the flour with the salt. In another bowl, whisk together the egg and 60 ml (approximately 1/4 cup) of water and add to the flour. Stir in the milk and mix until smooth.
Brush the wells of a popover mold with oil and place in the oven for 5 minutes. Remove the pan from the oven and divide the batter among the wells. Bake on the middle rack of the oven until golden brown 10-15 minutes.