In a bowl, combine the chicken, olive oil, dried oregano, cumin, salt and pepper. Toss until the chicken is evenly coated.
Heat a grill, grill pan or cast iron skillet over medium-high heat. When hot, add the chicken and cook until golden brown and cooked through, about 4 minutes per side. Transfer the cooked chicken to a cutting board.
Reduce heat to medium. Add the corn to the skillet and cook, rotating every 2 minutes, until the kernels are tender and the corn is lightly charred, 8 to 10 minutes. Remove from heat and let cool.
In a large bowl, add the romaine, corn, pumpkin seeds, cherry tomatoes, and red onion. Cut the chicken into bite-size pieces and add to the salad. Remove the kernels from the ear of corn and add to the salad. Add the desired amount of dressing and toss until well-coated. Add the avocado and gently toss once more to combine.
