Final answer:
When drying choux dough, look for a thin film at the bottom of the pan, the dough pulling away from the sides and forming a cohesive mass, and it being glossy and holding a peak after the eggs are added.
Step-by-step explanation:
The process of drying choux pastry is critical to achieving the right texture for recipes such as eclairs and cream puffs. When you are preparing choux dough, there are several visual clues to look for to determine if it has dried sufficiently. Firstly, you'll notice that the dough will form a thin film at the bottom of the pan which indicates that much of the moisture has evaporated. Secondly, the dough will pull away from the sides of the pan and will clump together around the spoon or spatula used for stirring, forming a smooth, cohesive mass. Lastly, when you've finished adding the eggs, the dough should be glossy and hold a peak when lifted with your spatula. These visual clues will help you ensure that your choux pastry is ready for piping and baking.