In a mixing bowl, combine olive oil, fresh lemon juice, lemon zest, minced garlic, instant chicken bouillon, chili powder, chili flakes, ground cumin, kosher salt, and freshly ground black pepper. Whisk together until well blended.

Take the boneless skinless chicken thighs and coat them generously with half of the marinade mixture. Place the chicken in a resealable bag or container, sealing it well to prevent leaks.

Refrigerate for at least 2 hours, or overnight if possible.

About 15 minutes before cooking, remove the chicken from the refrigerator to allow it to come to room temperature. Heat a cast-iron grill pan over medium-high heat, adding the remaining olive oil.

Carefully place the marinated chicken thighs onto the grill pan. Grill for 4–5 minutes on one side until browned and you see clear grill marks. Flip and continue cooking for another 4–5 minutes, ensuring it reaches an internal temperature of 165°F.

Once cooked, remove from heat and let rest for a couple of minutes. Drizzle reserved marinade over the chicken before serving.