In a small bowl stir together the mayonnaise, sour cream, lime juice, cilantro and garlic until combined. Cover and refrigerate until ready to use. The sauce can be made up to 2 days in advance.
For the corn ribs:
Heat oven to 400ºF (200ºC).
Place a dish towel under a cutting board to keep it from slipping. Hold the corn cob on its end securely and use a sharp knife to make 4 vertical cuts into the corn cob so it breaks into 4 “ribs”.
Arrange the strips of corn in an even layer on a baking sheet and drizzle with the oil, turning to coat. Bake the corn until the kernels are tender and the corn is slightly charred, about 25 to 30 minutes.
Arrange on a serving platter and squeeze lime over the top. Season the corn with the Tajin and serve with the cilantro lime sauce.