Using a food processor, puree the roasted red pepper. In a large Dutch oven, heat the olive oil over medium-high heat. Stir in the onion, garlic and serrano and cook until just softened, about 2 minutes. Lower the heat to low and whisk in the flour until combined. Whisk in the tomato paste and red pepper puree, then the coconut milk and clam juice. Add the celery, potato and lima beans and bring to a boil. Lower the heat to medium-low and cook, covered, for 15 minutes.
Add the shellfish and cook until the shells open, about 5 minutes; discard any that do not open. Stir in the shrimp and cook until just opaque, about 2 minutes. Season with salt and pepper. Top with the cilantro.