Pour off all but 1 tablespoon fat from pan. Return pan to high heat and add shallot and poblano; sauté, stirring and flipping frequently, until lightly browned and fragrant, 1 to 2 minutes. Add cumin and continue to cook 30 seconds. Transfer pan contents to bowl. Add tequila to pan off heat, reserving about 2 teaspoons, and place pan on high heat. Light tequila on fire with long match or kitchen lighter. Let flames subside. Add chicken broth and 2 teaspoons lime juice. Reduce to 1/3 cup (about 6 minutes). Add remaining 2 teaspoons tequila, remaining teaspoon lime juice, and any meat juices to pan. Remove from heat and whisk in cold butter, cilantro, poblano, and shallot; season to taste with salt and pepper. Spoon sauce over steaks and serve immediately.

Makes 2/3 cup