Black Bean and Chorizo Tortas with Tomatillo Salsa

chorizo sausage, casing removed (about 1 cup)

olive oil, divided

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cooked black beans

(2 15 oz. cans), with liquid*

Salt

sandwich rolls, split

About 6 oz. queso fresco or other fresh cheese, sliced ¼-inch thick

Tomatillo salsa 

Sliced avocado