Example.cshtml

<select asp-for="Organization" asp-items="ViewBag.Organizations" class="form-control custom-select">
    <option>Please select an Organization</option>
</select>

ExampleController.cs

public async Task<IActionResult> CreateGroup()
{
     ViewBag.Organizations = new SelectList(await _context.GetOrganizations(),"OrganizationGuid","Name",{hardcoded-guid here});
     return View();
}