Season the chicken thighs with the garlic powder, Blackstone Dill Pickle Seasoning, black pepper, and olive oil. Let the chicken marinate while you preheat the Blackstone griddle.
Preheat the griddle to medium heat and add the cooking oil. Cook the chicken until golden brown and fully cooked.
While the chicken cooks, add the frozen corn and peas and carrots to another area of the griddle. Cook until heated through and lightly charred. This step is optional but adds extra flavor.
Remove the chicken from the griddle and chop it into small pieces.
In a large bowl, combine the chopped chicken, corn, peas and carrots, jalapeños, romaine lettuce, mayonnaise, mustard, pickled jalapeño juice, salt, and black pepper. Mix until well combined.
Refrigerate for about 30 minutes, or until chilled.
