Place the chicken breasts in a large saucepan and sprinkle with 1 teaspoon kosher salt; cover with cold water so the chicken is submerged.
Bring the water to a boil over high heat, then reduce to medium and simmer until the chicken is cooked through and no longer pink in the center, about 12–15 minutes (22–25 minutes if frozen).
Transfer the cooked chicken to a large mixing bowl and shred it using two forks or tongs.
Drain the poaching liquid from the saucepan, then return the shredded chicken to the pan.
Add the salsa, cumin, garlic powder, onion powder, paprika, chili powder, 1/2 teaspoon kosher salt, and 1/4 teaspoon pepper to the pan; stir and bring to a gentle simmer over medium heat for 3–5 minutes until heated through. Add 1 tablespoon water if the chicken seems dry.
Remove from heat and stir in the lime zest and lime juice.
Serve the shredded chicken on warmed tortillas and top with avocado, cheese, sour cream, jalapeños, or other desired toppings.