Bring a large pot of salted water to a boil. Add the pasta and cook according to the package instructions for al dente. Drain and rinse well with cold water.
Heat a large skillet over medium high heat. Add the oil if using. Add the corn and cook 5-6 minutes, until golden.
Add the onion, poblano pepper, tajin, salt, and pepper. Cook another 3-4 minutes, stirring occasionally, until the onion is translucent.
In a small bowl whisk together the dressing ingredients.
In a large bowl add the pasta, corn mixture, feta, and cilantro. Pour on the dressing and toss well. Serve with a garnish of fresh cilantro.