Chimichurri Beef Sandwiches

Ingredients

• 120 ml (½ cup)water
• 120 ml (½ cup)rice vinegar
• 38 g (3 tablespoons)sugar
• 15 ml (1 tablespoon)kosher salt
• 1bay leaf
• 1sprig fresh thyme
• 3whole peppercorns
• 2.5 ml (½ teaspoon)crushed red pepper flakes
• 1 largered onion, thinly sliced
• 120 ml (½ cup)mayonnaise
• ½ mediumlemon, zested and juiced
• 1 bunchfresh flat-leaf parsley, stems removed and finely chopped
• 30 ml (2 tablespoons)red onion, finely chopped
• 15 ml (1 tablespoon)red wine vinegar
• 1 clovegarlic, minced
• 2.5 ml (½ teaspoon)crushed red pepper flakes
• to tastesalt and pepper
• 1petite French bread baguette
• 142 g (5 ounces)sliced deli roast beef
• 2 slicesSwiss cheese
• 57 g (2 ounces)roasted sweet red pepper strips

Instructions

1. 1

   Pickle the onions

   Combine the first eight ingredients in a small saucepan and bring to a boil. Put the sliced onion in a large jar or resealable container, then pour the hot brine over it. Leave to cool to room temperature, cover and refrigerate.

2. 2

   Mix the mayonnaise

   Whisk all the chimichurri mayonnaise ingredients together in a small bowl. Cover and refrigerate until chilled.

3. 3

   Build the sandwich

   Slice the baguette lengthwise into two halves and spread chimichurri mayonnaise over both cut sides. Layer the roast beef, Swiss cheese, roasted red peppers and about 28 g (1 ounce) of the pickled onions on the bottom half. Put the top half in place and cut the sandwich in half to serve.

What is a chimichurri beef sandwich?

This is a filled baguette built around roast beef, cheese, sweet roasted peppers and tangy pickled onion. Chimichurri is an herb-and-vinegar sauce associated with Argentina and Uruguay; here, parsley, garlic, lemon and vinegar are folded into mayonnaise for a creamy sandwich spread.

The combination works because the rich beef and mayo meet sharp, herby flavours and a little chilli heat. Pickling the onion separately also lets you add brightness without making the bread soggy.

Nutrition and macros by portion

The nutrition label shows one serving as written: 1334 calories, 46g protein, 84g carbs, 91g fat.

The baguette supplies most of the carbohydrates, while mayonnaise contributes much of the fat; the roast beef and Swiss cheese provide most of the protein. Pair the sandwich with a green salad or fresh vegetables for a more balanced plate.

The pickled red onions

Hot brine: bringing the water, rice vinegar, sugar, salt, spices and herbs to a boil helps dissolve the seasonings before they meet the onion. Pour it over the slices while hot, then let the mixture cool before covering and refrigerating.

Slicing: cut the onion thinly so the brine can reach it evenly and the pieces are easy to bite through in the sandwich. The recipe uses about 28 g (1 ounce) for assembly; keep the rest chilled for another use.

Making the chimichurri mayo

Herbs and aromatics: finely chopped parsley distributes through the mayonnaise, while garlic, lemon zest and juice, red wine vinegar and chilli give it a lively, savoury edge. Remove the parsley stems as directed for a smoother spread.

Chilling: resting the mixture in the fridge until chilled gives the flavours time to mingle and makes it easier to spread. Taste and adjust the salt and pepper before assembling.

Layering for a good bite

Spread: cover both cut faces of the baguette with the mayonnaise so its flavour reaches the bread from top to bottom. A consistent layer helps the ingredients stay in place.

Order: put the roast beef on the bottom, followed by Swiss cheese, roasted peppers and pickled onion. Keep the onion quantity close to the recipe’s 28 g (1 ounce) so its acidity complements rather than overwhelms the filling.

Choosing and preparing the bread

Baguette: a petite French baguette gives the filling a crusty exterior and a soft centre. Slice it lengthwise in one piece to create a top and bottom that are easy to fill.

Serving: once the top is replaced, cut the sandwich in half as directed. If the baguette is especially crusty, use a serrated knife and a gentle sawing motion to keep the filling from shifting.

When to prepare each part

Make ahead: the onion pickles need to cool and then be refrigerated, and the mayonnaise is also chilled before use. Those two components can be prepared ahead, leaving only the baguette and filling to assemble at serving time.

Final assembly: add the spread and fillings shortly before eating to preserve the bread’s texture. The stated 45 minutes is the total time provided for the recipe.

What to serve alongside

Fresh sides: a green salad or crisp sliced vegetables provide a light contrast to the beef, cheese and mayonnaise. Keep any dressing or dip separate so the sandwich stays intact.

For a more substantial meal, serve with a bowl of soup or a modest portion of crisps. The sandwich is already generously filled, so a simple side is often plenty.

Recipe notes & tips

• Finely chop the parsley so it spreads evenly through the mayonnaise.
• Let the pickled onions cool before covering the container and putting it in the fridge.
• Drain the pickled onion and roasted peppers well before adding them to the baguette.
• Season the mayonnaise gradually, tasting before adding more salt.
• Assemble the sandwich just before serving to help keep the bread from becoming soggy.

Variations

• Extra heat: increase the crushed red pepper flakes in the mayonnaise to taste.
• More herbs: add a little extra finely chopped parsley for a greener, more pronounced spread.
• Different cheese: use provolone in place of Swiss for a milder, stretchy layer.
• Crisp greens: tuck a few lettuce leaves into the sandwich just before serving.
• Smaller portions: cut the filled baguette into shorter pieces for a sharing platter.

Common mistakes to avoid

• Covering hot onions: trapping heat too soon can build condensation; let the onions cool to room temperature first.
• Thick onion slices: they can be harder to bite through; slice the red onion thinly.
• Wet fillings: excess brine or pepper juices can soften the bread; drain them before assembling.
• Uneven spread: bare patches leave some bites less seasoned; spread the mayonnaise across both cut surfaces.
• Overfilling the baguette: too much filling can make it difficult to cut and eat; use about 28 g (1 ounce) of pickled onion as specified.

How to store

Refrigerate the pickled onions and chimichurri mayonnaise in covered containers; use within 3–4 days for best quality. Once assembled, the sandwich is best eaten straight away, as the bread softens in storage.

Frequently asked questions