How to Make It
Heat the oil in a deep, nonreactive, medium skillet or shallow flameproof casserole. Add the onion, season with salt and cook over moderate heat until translucent.
Add the chile strips, cover the pan and cook until just tender but not soft, about 4 minutes. Add the beer, increase the heat to high and boil, uncovered, until it is absorbed by the chiles, about 7 minutes.
Spread the slices of cheese over the chiles and heat until melted. Serve immediately.