Pan-Seared Tuna Over Buttery Mash with a Chilli–Lime Soy Drizzle

Some dishes begin with the protein, but this one starts with the chilli lime soy drizzle—a glossy, spicy lime soy sauce that brings brightness, heat, and depth to everything it touches. This quick chilli lime soy sauce is the star of the plate, transforming simple seared tuna steak and buttery mash into something vibrant, modern, and full of flavour. If you love a spicy sauce for fish, this drizzle will become a regular in your kitchen.

The chilli comes from my own Box of Fire—a collection of fresh chillies from Almería that fuels much of my rural Andalusian cooking.

Why This Chilli Lime Soy Drizzle Works

This chilli lime soy drizzle hits all the right notes: salty soy, sharp lime, gentle sweetness, and the clean heat of a fresh red chilli. It’s a flexible soy lime dressing that works on tuna steak, chicken, roasted vegetables, noodles, or even grilled prawns. The balance of lime, soy, honey, and chilli creates a spicy lime soy sauce that’s bold but not heavy—ideal for quick weeknight cooking, and an easy sauce for tuna steak when you want something with a bit of fire.

Seared Tuna Steak with Chilli Lime Soy Drizzle and Buttery Mash

Serves 1

Ingredients

For the tuna steak

• 1 tuna steak, 225 g raw weight, about 2.5–3 cm thick
• A splash of oil for the pan

For the buttery mash

• 300–350 g floury potatoes (Maris Piper, King Edward, or any "para cocer" potato in Spain)
• 40–50 g butter
• 3–4 tbsp unsweetened almond milk
• 1 tbsp extra virgin olive oil
• Sea salt and white pepper

For the chilli lime soy drizzle (adjust quantities as needed)

• 3 tbsp soy sauce
• 1 tbsp lime juice
• Zest from ½ lime
• 1 tsp honey or brown sugar
• ½ red elongated chilli, finely chopped
• 1 tsp grated ginger (optional)
• 1 tbsp neutral oil
• Black pepper

Method

1. Cook the mash. Peel the potatoes and cut them into even chunks. Start them in cold, salted water, bring to the boil, then simmer for 15–20 minutes until a knife slides through. Drain well and steam dry in the warm pot for 30–60 seconds. Mash, then beat in the butter, the warmed almond milk a little at a time, and the olive oil. Season with sea salt and white pepper. My full method is in the Perfect Mashed Potato recipe. Keep the mash warm while you cook the tuna.
2. Make the drizzle. Mix the soy, lime juice, zest, honey, chilli and ginger. Warm the oil in a small pan, add the mixture and bubble for 30–45 seconds until slightly thickened. Remove from the heat, add pepper, and adjust: more lime for brightness, more honey if the chilli bites, or a splash of water if it's too intense.
3. Sear the tuna steak. For a properly seared tuna steak, get a pan very hot with a splash of oil. Sear the tuna on high heat for 1½–2 minutes per side, aiming for an internal temperature of 48–52°C and a blush-pink centre. Overcooked tuna becomes dry and loses its steak-like texture. It's the same method as my Pan-Seared Tuna with Garlic Spinach and Lemon Drizzle.
4. Plate. Spoon the buttery mash into a soft oval. Slice the seared tuna steak and fan it across the mash. Arc the chilli lime soy drizzle across the plate from top right to bottom left, and let a few drops pool near the mash for contrast.
5. Garnish. Add thin slices of the same red chilli, chives, coriander or spring onion, and a lime zest curl if you like.

This layout highlights the sauce—the true hero of the dish. The richness of the mash softens the heat and lets the drizzle shine.

Why You’ll Make This Spicy Sauce For Fish Again

• It’s a quick chilli lime sauce ready in under a minute.
• It uses fresh chillies for clean, natural heat.
• It pairs with tuna, chicken, vegetables, noodles, or rice.
• It’s flexible, bright, and perfect for anyone who loves a spicy lime soy sauce.

For another buttery mash pairing, this time with cod and a lemon habanero glaze, try my Pan-Fried Cod Loin with Buttery Mash and Lemon Habanero Glaze. More tuna steak ideas: Tuna Steak with Sesame Oil and Tahini Dressing and Mediterranean Tuna Steak with Warm Tomato and Fennel Compote.

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Footnote

This seared tuna steak recipe is part of my Tuna Steak Recipes collection and my Inland Fish and Seafood hub, a collection of resourceful ways to prepare the sea's bounty from the heart of rural Spain.
Find more recipes and food adventures here.
Wonky photos, proper food, genuine adventures – The Flexible Chef