In a large cast-iron skillet, heat the oil over medium-high heat until it shimmers.
Arrange the mushrooms in a single layer. Cook, undisturbed, for about 5 minutes, or until beginning to brown.
Add the salt, stir, and continue cooking for about 3 minutes, or until their liquid is absorbed. Continue cooking, stirring now and then, for about 5 minutes more, or until some of the edges crisp.
Stir in the BBQ sauce and continue cooking, stirring, for about another 2 minutes, until the sauce bubbles and reduces to a thick coating.
Divide the mushrooms between the rolls and top with coleslaw.