BBQ Barramundi Burger Grilled Cos

The first time I grilled lettuce for a burger, my neighbor peeked over the fence and asked if I'd lost my mind. Now it's the only way I'll serve a fish burger. Something about that smoky sweetness against the flaky barramundi just works.

I made these for a summer backyard gathering last year and watched three self-proclaimed fish haters go back for seconds. The charred cos lettuce was the conversation starter nobody expected.

Ingredients

• 4 barramundi fillets (150g each, skinless): This Australian native has a buttery texture that grills beautifully without falling apart
• 2 tbsp olive oil plus 1 tbsp for lettuce: Creates that gorgeous char and keeps everything from sticking to the grates
• 1 lemon (halved) plus zest: Grilling the lemon halves mellows the acidity and brings out this incredible floral sweetness
• 2 jalapeños, halved and seeded: Grilling tames their bite while adding this smoky depth that fresh peppers just can't match
• ½ cup good-quality mayonnaise: The canvas for our tartare sauce, so don't skimp on quality here
• 2 tbsp capers, finely chopped: These little salty buds punch up the sauce and cut through the rich fish
• 1 tbsp each fresh dill and parsley, chopped: Fresh herbs bring brightness that balances all that smoky grilled flavor
• 1 small shallot, finely diced: Milder than onion and perfect for a delicate sauce like this
• 1 tsp Dijon mustard: Just enough tang to tie everything together without overpowering the fish
• 1 large head cos lettuce, separated into leaves: The sturdy leaves hold up to grilling and give you this satisfying crunch in every bite
• 4 brioche or burger buns: Brioche's slight sweetness pairs perfectly with the smoky grilled elements
• 8 thin slices ripe tomato and 8 cucumber slices: Fresh, cool contrast to all that warm smoky goodness

Instructions

Fire up the grill:

Get your BBQ or grill pan heating to medium-high, hot enough that you can only hold your hand above it for a few seconds

Marinate the fish:

Whisk together olive oil, lemon zest, minced garlic, salt, and pepper, then coat the barramundi fillets and let them sit for 10 minutes while you prep everything else

Get your garnish ready:

Brush those cos lettuce leaves with olive oil and slice your tomatoes and cucumbers thinly so they're ready to assemble

Grill the aromatics:

Throw lemon halves cut-side down and jalapeños on the grill, letting them char for 3 to 4 minutes until softened and gorgeous, then chop the peppers and squeeze that precious grilled lemon juice

Make the magic sauce:

Mix the mayonnaise with grilled jalapeños, 2 tablespoons of that smoky lemon juice, capers, herbs, shallot, Dijon, salt, and pepper, then pop it in the fridge to chill

Grill the barramundi:

Cook those marinated fillets for 3 to 4 minutes per side until just opaque and lightly charred, being careful not to overcook the delicate fish

Char the lettuce:

Grill the cos leaves for just 1 to 2 minutes per side until slightly wilted with gorgeous grill marks

Toast the buns:

Give your burger buns a quick toast on the grill to build structure and add another layer of smoky flavor

Build your masterpiece:

Spread that grilled lemon jalapeño tartare on both buns, then stack with grilled cos lettuce, barramundi, tomato, and cucumber before closing it up

Serve immediately:

Get these beauties onto plates while the fish is still warm and the lettuce still has that perfect texture from the grill

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These burgers have become my go-to for summer evenings when everyone's gathered around the outdoor table and nobody wants anything too heavy. The way the grilled flavors dance together makes every bite feel like a little celebration.

Choosing the Right Fish

If you can't find barramundi, snapper and cod work beautifully here too. You want something firm enough to hold its shape on the grill but with that tender flake that makes fish burgers so satisfying.

Grilling Lettuce

Charred cos lettuce is a game changer you'll want to use everywhere. The heat wilts it slightly while bringing out this natural sweetness that pairs perfectly with smoky grilled fish.

Making the Tartare Ahead

This grilled lemon jalapeño tartare actually gets better after a few hours in the fridge. The flavors meld together beautifully, so feel free to make it up to a day before your burger night.

• Let the sauce come to room temperature before serving for the best texture
• Taste after chilling and adjust the lemon juice if needed
• Double the batch because you'll want to put it on everything

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There's something about a fish burger done right that feels like a tiny vacation, even if you're just eating at your own kitchen table.

Recipe FAQs

→ What fish works best for this burger?

Barramundi is ideal for its firm texture and mild flavor, but you can easily substitute with snapper, cod, or any other firm white fish that holds up well on the grill.

→ How spicy is the jalapeño tartare?

The tartare has a mild to medium heat level. Grilling the jalapeños mellows their spice, while the mayonnaise and herbs create a balanced, zesty sauce. Add extra seeds or hot sauce if you prefer more kick.

→ Can I cook this indoors?

Absolutely! Use a grill pan or heavy skillet over medium-high heat. You can also use a panini press to achieve those attractive grill marks on the fish and lettuce.

→ What sides pair well with this burger?

Try crispy chips, a fresh Greek salad, or roasted potato wedges. The bright flavors also complement lighter sides like quinoa salad or grilled asparagus.

→ How do I prevent the barramundi from sticking to the grill?

Ensure your grill is well-oiled and preheated to medium-high. The olive oil marinade also helps create a non-stick surface. Don't move the fillets too soon—let them develop a nice sear first.

→ Can I make the tartare sauce ahead of time?

Yes! The grilled lemon jalapeño tartare actually tastes better after resting for a few hours or overnight. Store it in an airtight container in the refrigerator for up to 3 days.