This example uses reqwest to send an HTTP request to httpbin. The parsed response contains an increment value (as provided in the request) that is finally sent to the main GUI thread.
This is the worst possible way to increment a counter, but it demonstrates awaiting async tasks without blocking the main GUI thread. It is also a very poor use of tokio. Awaiting the future in a thread with pollster is both easier and just as efficient. But if you actually need tokio, this is how to use it with egui.