Using kitchen shears, cut off the stems of the chiles and cut them open. Remove the seeds and veins and discard. Heat a cast-iron skillet over medium, then dry toast them for ~30-60 seconds per side, or until fragrant.
Bring a saucepan of water to boil, then turn the heat off, add the chiles in, cover the pot, and let them rehydrate for 10-15 minutes, or until pliable.
Add tomatoes, roughly chopped onion, and garlic cloves to another pot of water. Bring to a boil, then reduce the heat and simmer for 12-15 minutes.
Add the drained chiles, tomatoes, onion, and garlic to a blender along with the apple cider vinegar, 1 cup of vegetable broth, and all seasonings (except the bay leaves). Blend on high until smooth.
Pour the sauce through a mesh strainer into a large saucepan, working it through with a spoon or spatula. Add in 2-3 more cups of vegetable broth, and simmer for 35-40 minutes.