This Coconut Lime Fish Soup is one of those recipes that instantly transports you back to warm evenings and open-air markets. I first made it on a rainy spring night when I wanted something light but deeply satisfying. The combination of creamy coconut milk, bright lime, and pungent fish sauce felt like a small culinary escape. The fish stays tender and flaky, the broth is silky, and the herbs add an aromatic lift that makes everyone at the table lean in for another spoonful.

Over the years this soup has become my go-to when I want something that’s both comforting and elegant. I discovered the balance of flavors by starting with a simple coconut broth and gradually adjusting salt, acid, and heat. What makes it special is the contrast: the lush mouthfeel from the coconut milk, the sharp citrus from lime zest and juice, and the fresh herb finish that brightens each bite. It’s a weeknight winner that also shines when you’re entertaining because it looks beautiful in the bowl and feels thoughtfully plated without fussy techniques.

Ingredients

• White fish (1 pound): Use firm, flaky fillets like cod, halibut, or sea bass. Cut into bite-sized pieces so they cook quickly and evenly; fresh or thawed frozen fillets both work well.
• Vegetable oil (1 tablespoon): Neutral oil for sautéing aromatics. Can substitute with light olive oil or avocado oil for higher smoke point.
• Onion (1 medium): Yellow or sweet onion, chopped. Sweating the onion builds a sweet base that complements the tangy lime and savory fish sauce.
• Garlic (3 cloves) and ginger (1-inch): Minced finely. These provide the classic aromatic backbone common to Southeast Asian soups—fresh is best for bright flavor.
• Red bell pepper (1): Thinly sliced for color and crunch; it softens slightly in the broth while retaining brightness.
• Coconut milk (14 oz can): Full-fat yields the creamiest mouthfeel; shake the can before opening for even texture. If you prefer lighter soup, use light coconut milk.
• Fish stock or chicken broth (2 cups): Fish stock will deepen the oceanic notes, but good-quality low-sodium chicken broth is an excellent substitute.
• Fish sauce (2 tablespoons): The umami backbone. Taste carefully—brands vary in saltiness. Tip: add gradually and adjust at the end.
• Limes (2): Zest and juice. Zest adds aromatic oils; juice brightens the entire broth. Use fresh limes, not bottled juice.
• Sugar (1 teaspoon): Balances acid and salt. Simple granulated sugar or palm sugar both work.
• Red chilies (1–2): Sliced thin for heat. Adjust according to tolerance; remove seeds for milder spice.
• Cherry tomatoes (1 cup): Halved. They add bursts of sweetness and color to the soup.
• Fresh cilantro and Thai basil: Generous handfuls for garnish; they bring immediate aromatic brightness when added at the end.

Instructions

Prepare the aromatics: Heat 1 tablespoon vegetable oil in a large pot over medium heat. Add 1 chopped medium onion and cook until soft and translucent, about 5 minutes. This gentle sauté develops sweetness that balances the fish sauce and lime juice. Add garlic, ginger, and chilies: Stir in 3 minced garlic cloves, 1-inch grated ginger, and sliced 1–2 red chilies. Cook 1 to 2 minutes until fragrant, stirring constantly to prevent browning; you want the aromatics to release oils without scorching. Build the broth: Pour in 14 ounces coconut milk and 2 cups fish stock or chicken broth. Add 2 tablespoons fish sauce, zest and juice of 2 limes, and 1 teaspoon sugar. Bring the mixture to a gentle simmer, then reduce heat slightly to maintain a low simmer—vigorous boiling can split coconut milk. Add vegetables: Stir in the sliced red bell pepper and 1 cup halved cherry tomatoes. Simmer 5 to 7 minutes until the vegetables are tender-crisp. Watch for color and texture; peppers should still have a bit of bite. Cook the fish: Gently add 1 pound bite-sized white fish pieces to the simmering broth. Poach for 5 to 7 minutes until the fish is opaque and flakes easily with a fork. Do not overcook; remove from heat as soon as it’s just cooked through. Finish and serve: Taste and adjust seasoning with extra fish sauce or lime juice. Ladle into bowls and garnish with fresh cilantro and Thai basil. Serve immediately with lime wedges on the side.

Storage Tips

Store cooled soup in airtight containers in the refrigerator for up to 48 hours. If you plan to keep it longer, freeze in portions: use freezer-safe containers or heavy-duty bags, leaving 1 inch headspace. Thaw overnight in the refrigerator and reheat gently on low heat until warm. If the coconut milk separates after refrigeration, whisk vigorously or blend briefly with an immersion blender to restore creaminess. Avoid boiling during reheating to prevent curdling.

Ingredient Substitutions

If you don’t have white fish, shrimp or scallops make excellent alternatives; reduce poaching time for shrimp to 2–3 minutes. For a vegetarian version, substitute firm tofu and use vegetable broth plus a tablespoon of soy sauce in place of fish sauce (note: this makes it non-fish-based). If you prefer less fat, use light coconut milk or dilute full-fat with extra broth. Swap Thai basil with regular basil in a pinch, though the flavor will be milder.

Serving Suggestions

Serve in shallow bowls garnished with cilantro, Thai basil, thinly sliced chilies, and lime wedges. For a heartier meal, offer steamed jasmine rice or cauliflower rice on the side. A crisp cucumber salad or lightly dressed green salad complements the creamy broth. For an elevated dinner, serve with crusty bread to soak up the broth, or mini rice paper rolls as an appetizer to echo the soup’s Southeast Asian flavors.

Cultural Background

This soup draws inspiration from Southeast Asian coastal cooking where coconut and citrus are commonly paired with seafood. Variations of coconut-based broths are found from Thailand’s tom kha to Vietnamese and Malaysian coastal soups. Fish sauce contributes an essential umami note that many Southeast Asian kitchens use instead of or alongside salt. The result is a balance of creamy, sour, salty, and spicy flavors that reflect the region’s taste profile.

Seasonal Adaptations

In summer, add a handful of thinly sliced mango or extra cherry tomatoes for seasonal sweetness. In cooler months, swap in heartier veg such as sliced carrots and baby bok choy that will stand up to longer simmering. For a festive twist, stir in a spoonful of red curry paste and top with toasted coconut flakes. Herbs can be changed by season—use available fresh herbs to maintain brightness year-round.

Meal Prep Tips

Make the broth ahead and cool quickly before refrigerating. Portion broth into individual containers for quick lunches; store fish separately and poach fresh when ready to eat. If freezing, leave out the fresh herbs and lime juice—add them fresh when reheating for brightness. Use shallow containers for faster chilling. For grab-and-go weekday meals, pack rice separately and reheat both components before combining to preserve texture.

This soup is one of those recipes I keep returning to because it’s reliable, flexible, and always delicious. It’s a small ritual to grate fresh ginger, squeeze lime, and watch the broth become aromatic—simple steps that pay off with big flavor. Give it a try and make it your own by adjusting herbs, heat, and vegetables to suit what’s in season or in your pantry.