1) Load the slow cooker
Add sliced onion to the bottom of the slow cooker. Place chicken thighs on top.
In a small bowl, whisk together garlic, jalapeño (if using), chili powder, cumin, salt, smoked paprika, oregano, black pepper, orange juice, lime juice, tomato paste, and honey until the tomato paste is fully dissolved and the sauce looks smooth. Pour it evenly over the chicken.
2) Cook until shred-tender
Cover and cook on Low for 5 to 6 hours or High for 3 to 4 hours, until the chicken shreds easily with a fork and reaches 165°F in the thickest part.
3) Shred and boost the flavor
Transfer chicken to a large bowl and shred with two forks. Ladle in cooking juices starting with 1/2 cup, toss, then add more as needed so the chicken is juicy but not soupy.
Optional but very worth it: For extra punch, ladle about 1 cup of the cooking liquid into a small saucepan and simmer for 5 to 8 minutes until slightly reduced. Stir back into the chicken. Finish with an extra squeeze of lime if it needs brightness.
4) Make the mango salsa
In a bowl, combine mango, red onion, bell pepper, cilantro, lime juice, and salt. Taste and adjust with more salt or lime. If your mango is super sweet, an extra pinch of salt makes it pop.
5) Stir up the lime crema
In a small bowl, mix sour cream (or yogurt) with lime zest, lime juice, salt, and enough water to make it drizzle-able.
6) Warm tortillas and build tacos
Warm tortillas in a dry skillet, directly over a low gas flame for a few seconds per side, or wrapped in a damp paper towel in the microwave for 20 to 30 seconds. Fill with shredded chicken, top with mango salsa, and drizzle with lime crema. Add hot sauce if you want extra heat.
