Heat the grill or broiler to high. Arrange the red bell, poblano, jalapeno, Serrano and ear corn on the grill or under the broiler. Char, turning frequently, until the peppers have blistered and corn is starting to brown slightly. The smaller peppers will finish first, as they do, transfer to a small paper bag and close. Let the peppers sweat and cool, then remove the seeds and skin and dice. Cut the kernels from the cob. Put the peppers and corn into a small bowl and combine. Set aside. In a large Dutch oven, heat the oil over medium-high heat. Add the onion, yellow bell pepper and squash. Sauté until just starting to caramelize. Season with salt, pepper and cayenne. Stir in the garlic and rice and sauté for 3-4 minutes. Add the chicken stock, cover and cook for 10 minutes. Stir in peppers and corn, olives, black beans and tomatoes. Cook until rice is tender, about 6-8 minutes. Turn off heat, add cilantro and serve.