Mash avocados in a bowl just until they are mostly mashed but you still want some chunks.
Fold in jalapenos, red onion, lime juice, cilantro, cumin, kosher salt and garlic powder. Mix well. Fold in shredded chicken. Mix well. Cover and refrigerate for at least 30 minutes.
When ready to eat, toast the sourdough bread. Divide the chicken salad evenly between 4 slices of toasted bread. Top with remaining slices of bread. Serve.