Succulent pieces of warm, tender halibut swim in a rich, creamy mayo-based sauce that leans hard into the umami. Tangy pickled vegetables bring the crunch, and don’t forget the jalapeño for a bit of heat. After that first mouth-filling bite, you’ll know this is no ordinary sandwich!
In a small bowl, combine the mayonnaise, fish sauce, soy sauce, Worcestershire sauce, and sugar; stir until well combined. Set aside to allow flavours to meld.
In a small bowl mix together the salt and pepper.
Place fish into a dish and pat dry with paper towels. Season both sides of the fish portions with the salt and pepper mixture.
In a large skillet, heat the oil over medium-high heat until shimmering. If the fish has skin, place it skin-side down into the hot oil. Sear fish without moving for 2–3 minutes. Carefully flip the fish and fry the other side; 2–3 minutes or just until fish begins to flake when gently prodded with a fork. Remove from heat.
Cut each baguette lengthwise, but not all the way through. Partially hollow each baguette, creating space for the fish and filling.
Spread or drizzle mayonnaise evenly onto the bread.
Divide and layer in the sliced cucumbers, pickled carrots, and pickled daikon radish. Place a halibut fillet into the baguette. Layer in the cilantro and jalapeño.
Serve immediately.