• Peel and thinly slice the onion.
• Remove the stems from the shishito peppers.

In a large frying pan over medium-high heat, warm 1 to 2 teaspoons [2 to 4 tsp] oil until hot but not smoking. Add the onion and peppers, season with salt and pepper, and cook, stirring occasionally, until the onion is starting to soften and the peppers are shiny and starting to char and blister, 4 to 6 minutes. Transfer to a plate and season with salt and pepper. Add more oil between batches if needed. Wipe out the pan.
While the vegetables cook, prepare the tortillas.

In another large frying pan over medium heat, warm 2 to 3 tablespoons oil until hot but not smoking. Working in batches, add the tortillas and cook, turning once, until crisp, 2 to 4 minutes per side. Transfer to a paper-towel-lined plate and season with salt. Do not clean the pan.

• Cut a small corner from the chicken packaging and drain off any excess liquid. Transfer to a plate; pat dry with a paper towel. Season generously with salt and pepper.

In the same pan used for the tortillas, if dry, add 1 to 2 teaspoons [2 to 4 tsp] oil. Warm over medium-high heat until hot but not smoking. Working in batches if needed, add the chicken and cook, stirring once or twice, until lightly browned and almost cooked through, 5 to 7 minutes. Add more oil between batches if needed. [Return all the chicken to the pan.] Reduce the heat to medium and stir in the Yucatán simmer sauce base and 1 to 2 tablespoons water. Cook until the chicken is cooked through and the sauce is warm, 1 to 2 minutes.
While the chicken cooks, start the beans.

• Rinse the pinto beans.
• Measure ¼ teaspoon [½ tsp] cumin; save the rest for another use.

In the same pan used for the vegetables, combine the beans, ¼ teaspoon [½ tsp] cumin, and ¼ cup [½ cup] water and season with salt and pepper. Cook over medium heat, gently mashing the beans to form a coarse paste, until warmed through, 1 to 2 minutes. Remove from the heat.

Transfer the tortillas to individual plates. Spoon on the beans, top with the chicken, and garnish with the onion and shishito peppers. Crumble the queso fresco on top and serve.