In a large stock pot over medium heat, heat oil until shimmering. Add onion and a pinch of salt and pepper, and sauté until translucent, about 4 minutes. Add celery and jalapeño and cook until just tender, another 3 or 4 minutes.
Stir in curry paste until fragrant, about 30 seconds. Add chicken broth, coconut milk, red pepper and cabbage and bring to a simmer. Cook 10 minutes. Add cod chunks, shrimp, and calamari and continue to simmer until fish is cooked through, 5 to 10 minutes more.
Remove from heat and stir in fish sauce and lime juice. Add fresh cilantro just before serving.
Serves 6. Each serving has 8.58 g NET CARBS.Food energy: 318kcal Total fat: 19.83g Calories from fat: 178 Cholesterol: 171mg Carbohydrate: 11.03g Total dietary fiber: 2.45g Protein: 27.36g