In a small bowl, combine salt, pepper, garlic powder, cumin and oregano. Stir to combine and set aside.
Add onions, peppers, and garlic to the bowl of your slow cooker and sprinkle on half of the seasoning mixture. Stir to coat in seasoning then add the cubed pork. Sprinkle on the remaining seasoning mixture and stir to combine everything.
Pour the salsa over the pork and vegetables and gently stir before adding the lid and cooking on low for 8 hours, or high for 4 hours.
Once the pork is finished cooking, add the chopped cilantro and lime juice to the slow cooker. Stir to combine, then serve over rice and garnish with more cilantro, sliced radishes, and sour cream.