1Sort through the lentils and remove any small stones or debris. Unlike other dried legumes, lentils do not require soaking before cooking, which makes this dish relatively quick to prepare. Rinse the lentils thoroughly under cold running water and drain. Prepare all the vegetables: dice the onion, peel and dice the carrots into small pieces, peel and cube the potatoes into bite-sized chunks. Slice the chorizo into rounds about 1/4 inch thick - Spanish chorizo is cured and firm, so it slices easily. Dice the bacon or panceta into small pieces. Having everything prepared before you start cooking makes the process smooth and efficient.
2Heat the olive oil in a large Dutch oven or heavy-bottomed pot over medium heat. Add the diced bacon or panceta and cook for 3-4 minutes until it begins to render its fat and turn golden. Add the sliced chorizo and cook for another 2-3 minutes, stirring occasionally, until the chorizo releases some of its reddish-orange fat and becomes slightly crispy on the edges. The fat from the pork products will be beautifully tinted with the paprika from the chorizo - this is the flavor base of your stew.
3Add the diced onion to the pot with the chorizo and bacon. Cook for 4-5 minutes, stirring occasionally, until the onion softens and becomes translucent. Add the minced garlic and cook for another minute until fragrant. Add the smoked paprika and stir to coat everything - the paprika will bloom in the fat and become deeply aromatic. Be careful not to burn the garlic or paprika, as they can turn bitter. The mixture should smell wonderfully smoky and savory.
4Add the rinsed lentils, diced carrots, cubed potatoes, and bay leaf to the pot. Stir to combine everything with the chorizo and aromatics. Pour in the chicken broth and water - the liquid should cover the lentils by about 2 inches. If needed, add more water. Bring to a boil over high heat, then reduce the heat to low. Cover and simmer gently for 25-30 minutes, stirring occasionally to prevent the lentils from sticking to the bottom of the pot.
5Check the lentils and potatoes for doneness - the lentils should be tender but not mushy, and the potatoes should be easily pierced with a fork. If the stew is too thick, add more broth or water to reach your desired consistency. Traditional lentejas can range from brothy to quite thick, almost like a porridge - this is a matter of personal and regional preference. If the stew is too thin, continue simmering uncovered for another 10-15 minutes to reduce the liquid. The broth should be rich and flavorful, tinted orange from the chorizo and paprika.
6Season with salt and black pepper to taste. Be cautious with the salt initially as the chorizo and bacon add saltiness to the broth. Remove the bay leaf. Let the stew rest off heat for 5-10 minutes before serving - this allows the flavors to meld and the stew to thicken slightly. Ladle into deep bowls and garnish with fresh chopped parsley. Serve with plenty of crusty bread for dunking into the delicious broth. In Spain, lentejas con chorizo is often served as a first course followed by a lighter main dish, or as a complete meal on its own. The stew tastes even better the next day after the flavors have had more time to develop. Store refrigerated for up to 5 days - the stew will thicken considerably when cold, so add a splash of broth when reheating.