Process
Firstly, preheat the oven to 425ºF. Heat oil in a big ovenproof Dutch oven. Add onions to it and cook for about 5 minutes over medium-low heat, stirring occasionally. After 5 minutes, stir in bell peppers. Cover and cook for 5 minutes. When the peppers are done, lower the heat and add in garlic. Cook for 1 minute and then add chicken stock, red pepper flakes, rice, saffron, pepper, and salt. Bring the mixture to a boil.