Tunisian Egg Sandwich with Tuna, Harissa and Olives
A casse-croûte inspired by Tunisian street food: crusty baguette layered with jammy-firm hard-boiled eggs, olive oil–packed tuna, warm boiled potato, briny olives and capers, and a fiery harissa-lemon dressing. Nothing to bake or fry, just boil, chop and assemble.
- Prep
- 20 min
- Cook
- 20 min
- Wait
- 10 min
- Total
- 50 min
- Makes
- 4 sandwiches
Steps
Before you start
- Boil the eggs and potato first; both need time to cool before assembly, so start them together in separate pots.
- Harissa brands vary hugely in heat. Start with the lesser amount, taste the dressing, then add more.
- Drain the tuna well and pat the olives and capers dry so the bread stays crisp rather than soggy.
- Use a baguette with a crisp crust and soft crumb; stale bread is too tough, but very soft bread will turn mushy.
Boil the eggs
- Place the 4 cold eggs in a 3-quart saucepan and cover with cold water by 1 inch (2.5 cm).
- Set over high heat and bring to a full boil.
- As soon as it boils, cover, remove from the heat and let stand for 11 minutes.
- Meanwhile, fill a bowl with ice and water.
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Ready when: Yolks are fully set and pale yellow with no wet center when cut
Tip: Set a timer; even 3 extra minutes will give chalky, grey-green yolks.
Cook the potato
- While the eggs stand, put the potato cubes in a 1.5-quart saucepan, cover with cold water by 1 inch (2.5 cm) and add 1 tsp salt.
- Bring to a boil over high heat, then reduce to medium and simmer 8–10 minutes.
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Ready when: A paring knife slides into a cube with no resistance, but the cubes still hold their shape
Tip: Don't overcook; mushy potato will smear into the filling instead of staying in distinct pieces.
Chill and peel eggs
- Use a slotted spoon to move the eggs to the ice bath and cool 5 minutes.
- Drain the potato in a colander and let steam-dry for 5 minutes.
- Tap each egg all over on the counter, peel under a little cool running water, then cut into ½-inch (1 cm) chunks.
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Ready when: Eggs feel cool to the touch; potato cubes are no longer steaming
Make harissa dressing
- In a small bowl, whisk the harissa, olive oil, lemon juice, lemon zest and cumin until smooth and loose enough to drizzle.
- Season with a pinch of salt and several grinds of pepper.
- Taste on a piece of bread and add up to 1 tbsp more harissa if you want more heat.
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Ready when: Dressing is brick red, glossy and tastes bright, salty and spicy
Tip: Go easy on salt; the olives, capers and tuna are already salty.
Combine the filling
- In a large bowl, combine the cooled potato, chopped eggs, flaked tuna, olives, capers, parsley and tomato (if using).
- Pour over about two-thirds of the dressing.
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Ready when: Everything is lightly coated in red dressing, with distinct chunks still visible
Tip: Fold with a spatula rather than stirring so the egg and potato don't break down into a paste.
Taste and adjust
- Taste the filling and adjust with more salt, pepper, lemon juice or harissa as needed.
- Let it sit 5 minutes so the flavors meld while you prepare the bread.
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Ready when: Filling tastes well seasoned, tangy and spicy in every bite
Prepare the baguettes
- Cut each baguette crosswise into 2 pieces of about 8 inches (20 cm).
- Split each piece lengthwise with a serrated knife, leaving one long side attached like a hinge.
- Pull out a little of the soft crumb from the center to make a shallow channel.
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Ready when: Each piece opens like a book with a shallow trough for the filling
Tip: If the bread is a day old, warm it 3 minutes in a 350°F (175°C) oven first to refresh the crust.
Fill and serve
- Spoon about 1 cup (a quarter) of the filling into each baguette, pressing it in gently.
- Drizzle with the remaining dressing, then close and press firmly.
- Serve right away, cut in half if you like, with napkins.
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Ready when: Sandwiches are full but close fully, with a little red dressing seeping into the crumb
Tip: Assemble just before eating; after 30 minutes the bread turns soft.
Good to know
Tips
- Pat everything wet (tuna, capers, olives, tomato) dry so the filling stays chunky and doesn't soak through the bread.
- Pulling a little crumb from the baguette makes room for more filling and keeps the sandwich from squirting out the sides.
- Add the tomato only if it is truly ripe, and seed it well; watery tomato is the quickest way to a soggy sandwich.
- For a traditional touch, quickly brush the inside of the bread with a little extra olive oil before filling.
Make ahead
"The filling can be made up to 1 day ahead and refrigerated in an airtight container. Keep the bread separate and assemble just before serving. Boiled eggs can be cooked and kept unpeeled in the fridge up to 3 days."
Storage & reheating
"Assembled sandwiches are best eaten immediately and keep at room temperature no more than 1 hour. Store leftover filling in an airtight container in the fridge up to 2 days (the potato firms up; bring to room temperature 15 minutes before using). Not suitable for freezing because of the eggs and potato."
Substitutions
- harissa paste → Chili paste (such as sambal oelek) plus ½ tsp smoked paprika, or a pinch of cayenne mixed into tomato paste. Start with 1 tbsp of chili paste and adjust; the flavor will be less complex but still spicy.
- olive oil–packed tuna → Canned or jarred oil-packed sardines or mackerel, drained. Stronger flavor; use the same weight and flake gently.
- baguette → Soft but sturdy sandwich rolls or small ciabatta rolls. Use 4 rolls of about 4 oz (115 g) each; split and fill the same way.
- lemon → Lime juice and zest. Use equal amounts for a slightly sharper flavor.
