Step 1 In batches, on a grill or rack (such as a cooling rack) over an open stovetop flame, roast the tomatoes, onion and whole tortillas until lightly spotted with brown, then roast the chiles for a few seconds (after which they'll start to burn). Break the tortillas into pieces.
Step 2 Heat the olive oil in a medium saucepan. Add the garlic cloves and saute over medium-low heat for 1 to 2 minutes. Add the tomatoes, breaking them up with a wooden spoon. Add the onion, chiles, tortilla pieces, bay leaf and cilantro. Cook for 10 minutes.
Step 3Add the tomato juice, stock and water. Bring the mixture to a boil, then reduce the heat and simmer 15 minutes.
Step 4Remove from the heat and, using a blending wand or blender, puree the mixture, in batches if necessary, until smooth. Strain the mixture through a sieve, pressing on the solids; discard the solids.
Step 5Return the soup to the cleaned pan and add salt, white pepper and ground chile. Rewarm the soup; if it seems too thick, stir in additional stock or water. Garnish with fried tortilla strips and sour cream.