Heat the oven to 350°F. Wrap the tortillas in foil and bake until heated through, about 10 minutes. Turn off the oven; leave the tortillas in the oven until ready to serve.
Meanwhile, finely grate 3/4 tsp. zest from half of the lime. Cut the lime in half and squeeze the zested half to yield 1 Tbs. juice. Cut the other half into 4 wedges.
In a small bowl, stir the sour cream, 1/2 tsp. of the lime zest, 1/4 tsp. of the coriander, and a large pinch of salt; set aside.
Heat the oil in a 12-inch nonstick skillet over medium heat. Add the onion and cook, stirring often, until translucent, 2 to 3 minutes. Raise the heat to medium high and add the shrimp, the remaining 3/4 tsp. coriander, the cumin, pepper flakes, and 1/4 tsp. salt and cook, stirring constantly, until the shrimp are cooked through, about 2 minutes. Add the lime juice and remaining zest and stir to coat. Remove from the heat.
Put some of the cabbage, cilantro, and sour cream on each tortilla and top with the shrimp. Fold in half and serve immediately with the lime wedges on the side.