Remove stems from cilantro and tie together; save leaves for sauce.
Place cilantro stems, chicken thighs, water, onion, and garlic into a slow cooker. Season with 1 tablespoon cumin, 1 tablespoon chili powder, 1 tablespoon pepper, and 1 teaspoon salt.
Cook on Low until chicken is no longer pink in the centers and juices run clear, 8 to 10 hours. Transfer chicken to a plate and shred using 2 forks. Set aside. Reserve 1 to 1 1/2 cups cooking liquid. Let onion and garlic cool slightly, about 5 minutes. Dice and set aside.
Preheat the oven to 450 degrees F (230 degrees C). Spray a baking sheet with cooking spray.
Place tomatillos cut-side down and jalapeno onto the prepared baking sheet. Drizzle with canola oil.
Roast in the preheated oven for 25 minutes.
Remove from the oven and wrap jalapeno pepper in aluminum foil to let 'sweat' for about 10 minutes. Remove skin from jalapeno.
Transfer tomatillos, jalapeno, reserved cilantro leaves, green chiles, vinegar, cumin, chili powder, honey, pepper, and salt to a food processor or blender. Mix sauce until well combined.
Pour tomatillo sauce into a large pot and add shredded chicken, diced onion and garlic, and beans. Add reserved cooking liquid. Let simmer over medium-low heat for 15 minutes. Serve.