Protein Packed Keto Tuna Fish Sandwich

Today we’re dialing in a Keto fish sandwich, and yes, tin tuna is welcome at the party. We’re still using a sturdy, low-carb walnut bread that holds up to fillings, but now you’ll be able to pull this together with pantry staples in a snap.

I’ve swapped bread guilt for nutty goodness and a touch of playful humor, because who wants a boring lunch? This Keto fish sandwich recipe with tin tuna is my go-to when I want something quick, protein-packed, and lively enough to impress a weekend guest or a hungry coworker.

Why you’ll love this recipe

This keto fish sandwich with tin tuna nails that bright, ocean-fresh vibe without tipping the carb scales. The walnut bread brings a rich, earthy backdrop that stands up to the tuna and toppings—no soggy sandwich catastrophe here.

The tuna stays surprisingly moist when nicely dressed with mayo, lemon, and a hint of mustard. It’s easy to assemble in under 15 minutes, and the result can feel surprisingly gourmet for a weekday lunch. If you’ve been hunting for a keto tuna fish sandwich that actually delivers with pantry-friendly ingredients, this is your new go-to.

Ingredients (serves 1)

• 1/2 cup canned tuna (drained)
• 2 tablespoons mayonnaise or avocado mayo
• 1 teaspoon Dijon mustard
• 1 teaspoon lemon juice
• Salt and pepper to taste
• 2 slices keto-friendly walnut bread
• Lettuce, tomato, pickles
• Optional: capers or olives

Timing

• Prep time: 5–10 minutes
• Cook time: 0 minutes (if you’re serving cold) or 2–3 minutes for a light heat option

Step-by-Step Instructions

Step 1: In a small bowl, mix tuna with mayo, Dijon mustard, lemon juice, salt, pepper, and any optional capers or olives.

Step 2: Toast or warm the keto walnut bread briefly to help it hold up to the filling.

Step 3: Layer lettuce and tomato on one slice, add the tuna mix, and top with pickles.

Step 4: Close with the second walnut bread slice. Slice in half and serve right away, with a side of greens if you like.

Nutritional Information

• Servings: 1
• Per serving (approximate):
  • Calories: 320–380
  • Fat: 18–26 g
  • Carbohydrates: 6–10 g
  • Fiber: 4–6 g
  • Protein: 24–30 g Notes: Values vary with bread brand and exact tuna type.

Healthier Alternatives for the Recipe

• Swap mayo for a lighter yogurt-mayo blend to trim fat.
• Add a squeeze of extra lemon or a few capers for brightness without adding carbs.
• Use a bigger bed of greens or wrap in lettuce for ultra-low carbs.
• Try tuna packed in water only; oil-packed tuna adds fat, which can be fine if you’re aiming for satiety.

Serving Suggestions

• Serve with a simple greens salad or cucumber ribbons to balance the richness.
• A small side of pickled vegetables or a few olives can elevate the flavor without adding many carbs.

Common Mistakes to Avoid

• Overloading with mayo; keep the filling tight but not soggy.
• Skimping on toast; a quick toast helps the bread stand up to the filling.
• Not chilling the tuna mix briefly if you want a firmer texture for slicing.

Storing Tips for the Recipe

If you’re meal-prepping, store the tuna filling separately from the bread and toppings in the fridge for up to 1 day. Reassemble just before eating to keep texture crisp. If you have leftover tuna mix, it can be stored in a airtight container for up to 2 days and repurposed on salads or crackers.

What to serve with blackened tuna Note: Not applicable here; this version focuses on a tuna-filled keto fish sandwich using walnut bread.

FAQs

Is this truly a keto fish sandwich with tin tuna?

Yes—using canned tuna keeps carbs low while delivering protein and flavor, especially with the walnut bread.

Can I use canned tuna in oil?

You can, but drain well and pat dry to avoid sogginess; you may want to add a touch more mayo for moisture.

How do I keep the bread from drying out?

Lightly toast the bread and spread a modest amount of mayo to keep fillings moist without sogginess.

Can I make this ahead?

Yes—prepare the tuna filling and bread separately; assemble right before eating for best texture.