HERBY GRILLED PANINI WITH CARAMELIZED ONIONS, SPINACH, VEGAN OR REAL MOZZARELLA AND TOMATOES

Ingredients

• 90 ml (6 tbsp)extra-virgin Greek olive oil
• 1 mediumonion, halved and thinly sliced
• 90 g (3 cups)baby spinach, trimmed and torn
• 15 ml (1 tbsp)balsamic vinegar
• 30 ml (2 tbsp)fresh orange juice
• 1 large clovegarlic, minced
• to tasteGreek sea salt and freshly ground black pepper
• 8 thick slices or 4 piecessourdough bread or ciabatta, split with a serrated knife
• 340 g (12 oz)cashew-milk or fresh cow’s milk mozzarella, fresh and thinly sliced
• 12 large leavesfresh flat-leaf basil, whole
• 2tomatoes, cut into 12 rounds

Instructions

1. 1

   Cook the vegetables

   Heat 30 ml (2 tablespoons) of olive oil in a cast-iron or other heavy grill pan over medium-high heat. Add the onion; when it begins to sizzle, turn the heat to very low, cover the pan and cook for about 12 minutes, until soft and lightly browned. Stir in the garlic, then add the spinach and cook until wilted. Add the balsamic vinegar and orange juice, stir and cook for a few more minutes. Season lightly with salt and pepper, then remove the mixture and let it cool slightly. Wipe the pan clean.

2. 2

   Assemble the panini

   Use a serrated knife to split the ciabatta, or prepare two slices of sourdough for each panini. Layer the mozzarella, spinach and onion mixture, basil and tomato over the bottom half of each roll or slice of bread. Cover with the top half or remaining slice.

3. 3

   Grill until golden

   Heat another 30 ml (2 tablespoons) of olive oil in the grill pan. Place the sandwiches in the pan and press them down. Grill for about 4 to 5 minutes per side, pressing with a large spatula as they cook, until the bread is golden and the cheese has melted. Remove from the pan and serve.

What is a panini?

Panini is the Italian plural of panino, a filled bread roll or sandwich that is often grilled or pressed. This version brings together familiar Mediterranean flavours: mozzarella, tomato, basil and olive oil.

The cooked onion and spinach add a soft, savoury filling, while balsamic vinegar and orange juice give it a tangy, gently sweet note. Grilling crisps the bread and warms the cheese without requiring a dedicated press.

Nutrition and macros by portion

The nutrition label shows one serving as written: 640 calories, 23g protein, 57g carbs, 36g fat.

The bread and orange juice provide most of the carbohydrates, while mozzarella contributes protein and much of the fat; olive oil adds more fat. Serve a panino with a green salad or extra vegetables to round out the plate.

The onion and spinach filling

Low heat: after the onions start to sizzle, turn the heat right down and cover the pan. The gentle cooking gives them time to soften and lightly brown over about 12 minutes.

Spinach: add it after the garlic and cook only until wilted. The vinegar and orange juice go in afterwards, so their flavour can mingle with the vegetables before assembly.

Choose bread that can take the filling

Sourdough: thick slices provide a sturdy base for the cheese and vegetables. Use two slices per sandwich and keep the filling away from the edges to reduce spillage.

Ciabatta: split each piece with a serrated knife and layer the ingredients inside. Either option works well; the key is having bread substantial enough to press and grill.

Get the pan hot

A well-heated grill pan helps the bread brown and pick up grill marks. Once the filling is cooked, wipe the pan clean before warming oil for the sandwiches.

No panini press: set the sandwiches in the pan and press them with a large spatula as directed. For a heavier press, place a heavy pan on top of the sandwiches while they cook.

Watch the cheese and bread

The panini are ready when the bread is golden and the mozzarella has melted, which the recipe estimates at about 4 to 5 minutes per side. Press gently and evenly so the sandwiches flatten without forcing out too much filling.

If the bread is browning before the cheese melts, lower the heat and give the sandwiches a little more time. Let the vegetable mixture cool slightly before assembling to keep the bread from becoming wet.

Serve them while warm

These panini are best served just after grilling, when the bread is crisp and the mozzarella is soft. A simple green salad or a bowl of vegetable soup makes an easy accompaniment.

The filling has both savoury and tangy notes, so keep side dishes fresh and uncomplicated. Cut each sandwich in half for easier serving.

Recipe notes & tips

• Use a serrated knife to split the ciabatta without crushing it.
• Keep the onions covered over very low heat so they soften before browning too much.
• Wipe the grill pan after cooking the filling to keep stray bits from scorching.
• Let the spinach mixture cool slightly before layering it onto the bread.
• Press with a large spatula while grilling to help the sandwiches brown evenly.
• Cook in batches if needed so the pan is not crowded.

Variations

• Use vegan mozzarella: choose cashew-milk mozzarella for the plant-based option listed in the recipe.
• Choose sourdough: use two thick slices per sandwich instead of split ciabatta.
• Add extra basil: use a few more leaves for a stronger herbal note.
• Change the greens: swap in another tender leafy green, cooking it until wilted.
• Make it tangier: add a little more balsamic vinegar to the vegetable mixture.

Common mistakes to avoid

• Cooking onions over high heat: lower the heat after they sizzle so they soften rather than scorch.
• Adding spinach too early: stir it in after the garlic so it wilts without prolonged cooking.
• Overfilling the bread: keep the layers manageable so the sandwich stays together when pressed.
• Using a cold pan: heat the grill pan before adding the sandwiches for better browning.
• Pressing too hard: use steady pressure so the filling does not squeeze out.
• Grilling too quickly: lower the heat if the bread colours before the mozzarella melts.

How to store

Refrigerate leftover panini in a covered container for up to 2 days. Reheat in a frying pan over moderate heat, turning once, until warmed through and crisp again; the bread may soften in storage.

Frequently asked questions