Wash and dry produce.

Tear or roughly chop mushrooms. Halve, peel, and dice onion. Tear string cheese into 6 equal strands (12 strands for 4 servings). Roughly chop cilantro. Quarter lime.

Heat a drizzle of olive oil in a large pan over medium-high heat. Add mushrooms and half the onion; cook, stirring occasionally, until slightly crispy, 3-5 minutes. TIP: If pan seems dry, add another drizzle of olive oil.

Remove pan from heat; add Mexican Spice Blend, stock concentrate, half the Tex-Mex paste, half the chili powder, and 1½ cups water (all the Tex-Mex paste, all the chili powder, and 2½ cups water for 4 servings). 

Return pan with mushroom mixture to heat; bring to a boil, then reduce to a simmer. Cook, stirring occasionally, until broth has reduced slightly and mushrooms are tender, 4-6 minutes.

Remove from heat; using a slotted spoon, transfer mushrooms to a medium bowl, leaving broth behind. Transfer broth to a separate medium heatproof bowl. Wipe out pan. TIP: Use the back of a spoon to press on mushrooms while transfering them from the pan to press out any excess broth.

While mushrooms cook, place beans and their liquid in a small pot and season with salt and pepper. Heat over medium-high heat. Cook, stirring occasionally, until slightly softened and warmed through, 3-4 minutes.

Remove from heat; mash beans with a potato masher or fork until mostly smooth. Taste and season with salt and pepper.

Cover pot and set aside until ready to serve.

Place tortillas on a clean work surface; sprinkle one half of each tortilla with mozzarella. Top with mushrooms and string cheese. Fold tortillas in half to create quesadillas.

Heat a drizzle of olive oil in pan used for mushrooms. Add quesadillas; cook until tortillas are golden brown and cheese melts, 2-4 minutes per side. TIP: Depending on the size of your pan, you may need to work in batches. If pan seems dry, add another drizzle of olive oil.