How do I create a service to execute so I can return a response from my controller without waiting for the code in the service to run?

Question

This might sound like a newbie question, but any help in pointing me in the right direction would be apprecited.

If I have a controller (.Net) that I want to run some database transactions (fetch and update), is there a way to do it so that I can return a response quickly to the client without having to wait for the database stuff to save first?

Like some kind of background service? Any pointer to a link would be appreciated

ex.

[HttpPost("update")]
public async Task<IActionResult> UpdateAccount(AccountDto accountDto) 
{
     var user = await _userManager.FindByEmailAsync(accountDto.Email);

     // edit the user and save to db, but don't wait for it to finish before returning OK()
     user.firstName = "test";
     user.lastName = "test";
     await _userManager.UpdateAsync(user);

     return Ok();
 }