After flipping the egg, turn the heat down to low and keep cooking for another 40-50 seconds for a runny yolk. Cook it for longer if you prefer the yolk more well-done.
Again, your equipment may differ, so rather than relying on our 40-50 second guideline, it's best to take note of how your egg looks and feels to decide whether it's done or not.
A runny yolk will look plump. If you poke at it gently, it'll give way, and then spring back.
A cooked, solid yolk will look more flat. If you poke at it gently, it will give you a lot of resistance.
If you don't mind a really solid, very cooked yolk, you can speed up the cooking time by intentionally piercing the yolk and letting it cook via direct contact with the wok.
Assuming you're continuing to cook eggs (there will never be enough fried eggs!), you can slide the currently cooking egg up the side of the wok to finish cooking slowly.
Turn the heat back up to medium, and with the oil remaining in the wok, start cooking the next egg. If there's not enough oil to fry that egg, add as much as you need. Repeat the waiting, nudging, and flipping steps with your next egg, but don't forget to remove the egg that's waiting on the side of the wok whenever it's ready to your liking.
Once you've fried all the eggs that will make you content, turn off the heat and enjoy. Remember to season with salt if you didn't do so earlier.