There’s something undeniably sophisticated about a perfectly seared tuna steak – that beautiful contrast between the caramelized exterior and the ruby-red center. Pair it with a punchy wasabi aioli and a refreshing cucumber salad, and you’ve got yourself a restaurant-quality meal that happens to be gloriously keto-friendly.
Summer may be winding down, but my craving for light, vibrant dishes remains steadfast. This recipe delivers a triple threat of flavors and textures: the meaty satisfaction of barely-seared tuna, the creamy heat of wasabi aioli, and the crisp, vinegary bite of spicy cucumber salad. It’s the kind of meal that makes people forget they’re eating “diet food” and instead has them asking for seconds.
The Accidental Tuna Convert
I wasn’t always a tuna enthusiast. My first experience with ahi tuna was at a beachside restaurant in Hawaii, where I accidentally ordered it thinking it would be similar to the thoroughly cooked, canned variety I was familiar with. When a practically raw slab of fish arrived at my table, I nearly sent it back. But one tentative bite later, and I was converted. The buttery texture, the clean taste – it was nothing like I expected, and everything I didn’t know I needed in my culinary repertoire.
Now, it’s become my go-to impressive-yet-effortless dinner option, especially when I’m looking to elevate my keto menu beyond the usual suspects.
Why This Recipe Works
This dish hits all the right notes for keto enthusiasts without sacrificing an ounce of flavor. The tuna provides high-quality protein with virtually zero carbs, while the avocado oil and mayo-based aioli deliver healthy fats that keep you satisfied.
What’s more, this entire meal comes together in under 30 minutes, making it perfect for weeknight dinners when you want something special without spending hours in the kitchen. The cucumber salad can be prepared in advance, and the tuna itself cooks for literally one minute per side – that’s faster than waiting for your delivery app to process your order.
The wasabi aioli doubles as both a sauce for the tuna and a dressing for the cucumber salad, streamlining your prep work while maximizing flavor. And unlike many restaurant versions that sneak in sugar and starches, this recipe keeps things strictly keto without compromising on taste.
Ingredients
For the Tuna Steaks:
- 2 sushi-grade ahi tuna steaks (6 oz each, about 1-inch thick)
- 2 tablespoons avocado oil
- 1 tablespoon toasted sesame oil
- 2 teaspoons sesame seeds
- 1 teaspoon sea salt
- ½ teaspoon freshly ground black pepper
For the Wasabi Aioli:
- ½ cup mayonnaise (ensure it’s sugar-free for keto)
- 2 teaspoons wasabi paste (adjust to taste)
- 1 clove garlic, minced
- 1 tablespoon lemon juice
- ½ teaspoon salt
- ¼ teaspoon white pepper
For the Spicy Cucumber Salad:
- 1 English cucumber, thinly sliced
- ¼ cup thinly sliced red onion
- 1 small jalapeño, seeded and finely diced
- 2 tablespoons rice vinegar (unsweetened)
- 1 tablespoon toasted sesame oil
- 1 tablespoon tamari or coconut aminos
- 1 teaspoon erythritol or monk fruit sweetener
- 2 tablespoons fresh cilantro, chopped
- 1 teaspoon toasted sesame seeds
Instructions
Prepare the Wasabi Aioli:
- In a small bowl, combine the mayonnaise, wasabi paste, minced garlic, lemon juice, salt, and white pepper.
- Whisk until smooth and well incorporated. Taste and adjust the wasabi level to your preference.
- Set aside 2 tablespoons of the aioli to use in the cucumber salad.
Make the Spicy Cucumber Salad:
- In a medium bowl, combine the cucumber slices, red onion, and jalapeño.
- In a separate small bowl, whisk together the rice vinegar, sesame oil, tamari, sweetener, and the reserved 2 tablespoons of wasabi aioli.
- Pour the dressing over the cucumber mixture and toss gently to coat.
- Fold in the chopped cilantro and sesame seeds. Refrigerate while you prepare the tuna.
Cook the Tuna Steaks:
- Remove the tuna steaks from the refrigerator and pat them dry with paper towels.
- In a small bowl, mix the sesame seeds, salt, and pepper. Coat the tuna steaks on all sides with this mixture, pressing gently to adhere.
- Heat a heavy-bottomed skillet (preferably cast iron) over high heat until extremely hot, about 2 minutes.
- Add the avocado oil and sesame oil to the pan – they should shimmer immediately.
- Carefully place the tuna steaks in the pan and sear for exactly 1 minute on each side for rare, or 1.5 minutes for medium-rare. The outside should be caramelized and the inside should remain pink.
- Immediately transfer the tuna to a cutting board to prevent further cooking.
To Serve:
- Allow the tuna to rest for 2 minutes, then slice against the grain into ½-inch thick pieces.
- Arrange the cucumber salad on serving plates and place the sliced tuna alongside or on top.
- Drizzle the remaining wasabi aioli over the tuna or serve it on the side as a dipping sauce.
- Garnish with additional sesame seeds and cilantro if desired.
Tips and Variations
- Fish Quality Matters: For this recipe, sushi-grade tuna is non-negotiable. Your fishmonger should be able to recommend the freshest option.
- Temperature Control: Keep your tuna steaks in the refrigerator until just before cooking. Cold tuna will sear better on the outside while maintaining that rare center.
- Variation Ideas:
- For an extra kick, add a teaspoon of gochujang paste to the cucumber salad (check carb content).
- Swap the tuna for salmon if you prefer, but adjust cooking time accordingly.
- Add sliced avocado to increase the healthy fat content.
- For a more substantial meal, serve over cauliflower rice tossed with a little coconut aminos.
- Make Ahead: The wasabi aioli and cucumber salad can be prepared up to 24 hours in advance, though the cucumber might release some water over time. The tuna should be cooked just before serving.
Nutritional Information (Per Serving)
- Calories: 485
- Net Carbs: 4g
- Protein: 33g
- Fat: 36g
- Fiber: 2g
Note: Nutritional values are approximate and may vary based on exact ingredients used.
Ready to Wow Your Taste Buds?
This keto-friendly seared tuna with wasabi aioli and spicy cucumber salad proves that low-carb dining can be both elegant and exciting. It’s the perfect dish to serve when you want to impress dinner guests or simply treat yourself to something special.
Have you tried seared tuna before? I’d love to hear about your experience or any creative twists you put on this recipe! Drop a comment below or share your creation on social media and tag The Ketovore.
For more restaurant-worthy keto recipes that won’t kick you out of ketosis, check out our other seafood dishes on The Ketovore.
