In medium skillet, cook the bacon over medium heat until it renders most of its fat but does not brown, about 8 minutes. Add the onion and cook for 2 minutes, just until it is softened.
Increase the heat to medium-high. Add the meat and cook until it is no longer pink, about 5 minutes. Add the mushrooms and cook, stirring often, until the mushrooms soften and start to brown, 5 minutes.
Lower the heat to medium and add the jalapeño and garlic. Cook for 1 minute. Add tomato and stir to combine. Cook for another minute and add the beer, if using. Stir to combine and boil briefly, for 1 minute more. Season with salt.
Serve immediately with hot corn tortillas.