Puzzle.cs

using System;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        Util.Method(() => ActionMethod());
        Util.Method(ActionMethod); // Error CS0121  The call is ambiguous between the following methods or properties: 'Util.Method(Action)' and 'Util.Method(Func<Task>)'
    }

    private static void ActionMethod()
    {
    }
}

public static class Util
{
    public static void Method(Action action)
    {
    }

    public static void Method(Func<Task> actionAsync)
    {
    }
}