In a small bowl stir together chipotle chili powder, ground cumin, smoked paprika, salt, and black pepper, then set aside so the spices can blend and you’ll use it soon.
Heat a large skillet over medium-high and add oil, then corn, red onion, poblano, garlic, and half the seasoning blend. Cook about 5 minutes, stirring occasionally, until veggies soften and corn gets light char, adding a toasty aroma.
Meanwhile bring a pot of water to boil, cook ditalini according to package instructions, and reserve ¼ cup pasta water. Drain and rinse under cold water until cool to keep the pasta firm.
In a small bowl whisk together mayonnaise, Greek yogurt, lime juice, the remaining spice blend, and reserved pasta water until the mixture is creamy and thin enough to coat the salad.
Toss the cooled pasta, corn mixture, half the green onion, half the queso fresco, and the dressing in a large bowl until everything is evenly coated so you’ll have a cohesive salad.
Cover and refrigerate for at least 1 hour so the dressing firms up slightly and the flavors settle into the pasta.
Scatter the remaining green onion and queso fresco over the chilled salad before serving for a pop of color and contrast in texture.