Pre-heat the oven to 400°F.
Start by giving the tomatoes a good rinse and de-stem.
Roast the tomatoes in the pre-heated oven for 20 minutes.
Roughly chop the onion and peel 4 garlic cloves (leave whole as they will get blended eventually); cook the onion and garlic in a glug of oil, over medium heat, stirring regularly.
When the onion is starting to brown, add the onion-garlic mixture to a blender along with the roasted tomatoes and a single jalapeño; combine well; a single jalapeño will give the soup a whisper of heat, but feel free to add more to adjust to taste; scraping out the seeds of chipotles is optional.
Add the blender mixture back to the pan used to cook the onion.
Simmer the mixture, over medium heat, for few minutes, stirring regularly.
Add the 6 cups of stock, 1 teaspoon Mexican oregano, 1 teaspoon salt, and some freshly cracked black pepper; combine well.
Bring to a boil, then lower heat, cover and let simmer for 10 to 15 minutes.
As the soup simmers, make the crispy tortilla strips by chopping up 6 to 8 corn tortillas into slices.
Add a few tablespoons of oil to a frying pan, over medium-high heat.
When the oil is up to 350°F or when a single strip sizzles heavily, add the tortilla strips.
Cook for 30 to 60 seconds or until they are starting to turn darker in color; stirring regularly.
Using tongs, remove the cooked tortilla strips to a paper towel lined plate to allow them to cool.
Take a final taste of the soup for seasoning.
Add 1 to 2 cups of the soup to a bowl and load it up with the crispy tortilla strips.
Add toppings of choice.
Soup leftovers, placed in an airtight container will keep, in the refrigerator, for a few days; store extra tortilla strips separately, in a baggie, in the refrigerator.
