Meanwhile, chiles de árbol provide nutty, earthy undertones without shying away from spice. As a rule of thumb, remember that the smaller the pepper, the higher the heat. So for a tasty all ...

Add beef, breaking it up with a spoon while stirring. Season with salt, pepper and chile de árbol, if using. Sear until beef browns in spots, about 6 minutes. Add spinach and stir until wilted.