Heat the 200 ml vinegar in a saucepan over medium heat. Add the 50 g brown sugar and stir until completely dissolved.
Add the chipotles, chopped tomatoes, chopped onion, chopped garlic, bay leaf, ½ teaspoon salt, ½ teaspoon black pepper, ½ teaspoon cumin, and a pinch of cinnamon to the saucepan.
Bring to a simmer, cover with a lid, and simmer for 1 hour.
Remove the chipotles from the saucepan and set aside. Peel and remove the stems from each chipotle.
Strain the sauce through a fine sieve into a bowl, discarding the solids.
Return the peeled chipotles to the strained sauce and bring to a boil over medium-high heat. Boil uncovered for 2-3 minutes to reduce slightly (the sauce should remain pourable, as the chiles will absorb liquid and it will thicken further as it cools).
Pour the finished adobo sauce with chipotles into a sterilized 400 ml jar and seal tightly.