Grilled "Hot Tub" Beer Brats

fresh bratwurst sausage (about 8)

large Vidalia onions , quartered and sliced (for about 6 cups sliced)

cold butter , sliced

crushed red pepper flakes , or to taste, optional

Creole or Cajun seasoning (like Slap Ya Mama ), or to taste

black pepper , or to taste

large toes of garlic , smashed

to 3 pints of a pale lager or pilsner style beer

Pistolette mini po'boy rolls, or other hard roll such as semmels