Heat oil in a 12-inch nonstick skillet over moderate heat until hot but not smoking, then cook cumin and red pepper flakes, stirring, 1 minute. Add onion and bell pepper and cook, stirring, until softened. Add chorizo and saute over moderately high heat, stirring, until sausage begins to brown, about 3 minutes. Add rice, crumbling it, and salt. Saute, stirring, until some grains begin to turn golden, about 3 minutes. Add peas and saute, stirring, just until peas are heated through. Remove from heat and stir in pumpkinseeds and cilantro.