1. Position an oven rack in the center and preheat the oven to 350 degrees. Grease a 3-quart baking dish and set aside.
2. Scatter the bread cubes on 2 large baking sheets and toast them in the oven until they're dry and golden, about 5 minutes. Set the pans aside to cool the bread to room temperature.
3. Transfer the bread cubes to a large bowl. Add the dates and toss to distribute. Set aside.
4. Meanwhile, melt 2 Tbs. butter in a large saute pan over medium heat. Add the chorizo and Italian sausage and saute, breaking up the sausage with a wooden spoon, until the sausage is crumbled and golden brown, about 10 minutes. Add the onion, red and green bell peppers, celery, carrot, and garlic. Season with half the salt and cook, stirring occasionally, until the vegetables are soft and the onions are translucent, about 10 minutes. Add the remaining 2 Tbs. butter and stir until it melts. Stir in the chicken stock. Add the bread cubes and dates and the remaining salt, and gently stir to coat the bread cubes with the vegetable mixture.
5. Transfer the stuffing to the prepared baking pan and spread it out so the top is even. Sprinkle the cilantro over the stuffing. Cover the baking dish with foil, and bake on the center rack for 30 minutes. Remove the baking dish from the oven, remove the foil, and bake for about 30 minutes more, until the top is golden brown and a toothpick inserted into the stuffing comes out clean. Let the stuffing cool for 10 to 15 minutes before serving.