Preheat oven to 400° + place 4 tortillas on baking sheet, then brush lightly with oil + pinch of salt; bake 7-9 min until starting to crisp; divide to plates

Meanwhile, slice kernels off cob from 2 ears of corn; heat 1 tbsp oil in skillet over med-high + sauté corn with salt/pep 2-4 min until tender; set aside

Microwave beans in a covered, microwave-safe bowl 1 min (or warm in skillet 1-2 min); spread tortillas with refried beans + top with corn

Sprinkle tostadas with 1 tsp (or more!) taco seasoning + dollop on 1-2 tbsp sour cream