Preheat air fryer to 350°F + place 4 tortillas in air fryer basket, then brush both sides lightly with oil + pinch of salt; bake 4-6 min until starting to crisp

Meanwhile, thinly slice ¼-½ of onion then soak in cold water 15 min; drain + rinse onions

Heat 1 tbsp oil in skillet over med-high; pat shrimp dry + sauté with salt/pep 3-4 min until shrimp is pink, opaque + cooked through

Divide shrimp, onions + chopped cilantro to tostadas then drizzle with jalapeno crema + a squeeze of lime