How to Make It
Preheat the oven to 450°. In a small bowl, combine the chili powder, cumin, coriander and mustard. Stir in the oil. Season the meat with salt and pepper. Coat the meat with the spice mixture, cover and let stand at room temperature for 30 minutes.
Set the meat on a rack in a roasting pan and lay the bacon slices on top. Roast for 15 minutes. Reduce the oven temperature to 375° and roast for 25 to 30 minutes longer, or until an instant-read thermometer inserted in the thickets part of the meat registers 135° for medium rare. Discard the bacon, transfer the meat to a carving board and cover loosely with foil.
In a medium skillet, melt the butter. Add the onion and cook over moderately high heat, stirring often, until softened but not browned, about 5 minutes. Add the garlic and jalapeño and cook until the garlic is fragrant, about 1 minute. Stir in the white and black beans and the cilantro and cook until the beans are hot. Spoon onto plates.
Carve the meat into thin slices and arrange on top of the beans. Garnish with the tortilla chips and serve.