Cook the ChickenIn a medium pot, add the chicken breasts, ¼ onion, a generous pinch of salt, and enough water to cover. Boil until fully cooked (about 20–25 minutes). Remove the chicken and let cool slightly. Shred using two forks or a hand mixer. Reserve the broth!
Cook the Potatoes and VeggiesIn the same broth, add diced potatoes and boil until just tender (about 8–10 minutes). Add the frozen vegetable mix and cook for another 5 minutes until heated through. Drain and let cool slightly.
Combine Salad IngredientsIn a large bowl, mix the shredded chicken, cooked potatoes and veggies, and finely chopped lettuce.
Make the DressingIn a small bowl, whisk together mayo, sour cream, pickled jalapeño juice, salt, and pepper. Taste and adjust to your liking.
Toss and ServePour the dressing over the chicken mixture and toss until everything is evenly coated. Chill for 30 minutes if you have time—or serve right away!