boneless pork shoulder roast • olive oil • 15-ounce can great northern beans or navy beans, rinsed and drained • fresh tomatillos, husked and coarsely chopped, or two 11-ounce cans tomatillos, rinsed, drained, and coarsely chopped • chopped onion (1 medium) • 4-ounce can diced green chile peppers, undrained • garlic, minced • ground cumin • salt • 14.5-ounce can chicken broth • chopped fresh spinach leaves • lime juice •