MasterChef finalist Mark O'Brien: Here are my fish and veg options for summer barbeques

Dubliner Mark O’Brien, a finalist on ‘MasterChef: The Professionals’ 2026, shares his ideas for fish and vegetable barbecue options that will bring big flavour to your outdoor table

Mark O'Brien: "Fish takes barbecue flavour so well. It’s incredibly quick and delicious"

As soon as summer arrives, the search for the barbecue begins. After most of a year hibernating at the back of the shed or under the stairs, it gets dragged into daylight and pressed into service for future sunshine days.

Since we first encountered barbecues in Ireland and managed to move beyond the disposable charcoal-filled tinfoil trays, our food focus has gone far beyond the typical burger and sausage selection and towards something lighter. But make no mistake: While there might be more of an emphasis on fish and vegetables, the food still needs to be delicious and satisfying. Margate-based Dubliner Mark O’Brien is a chef who understands how to achieve that balance.

His recent stint as one of three finalists on 2026’s MasterChef: The Professionals — the first Irish chef to make it to that stage — saw him combine elements from his Irish upbringing with his love of open-fire cooking in the MasterChef kitchen. The affable O’Brien, a practitioner of low and slow American-style barbecue cooking, is the chef behind live fire pop-up Snake Oil Barbecue and a familiar face at the Big Grill, which will take place in Dublin’s Herbert Park from August 13 to 16.

Mark O'Brien at the Big Grill in 2024.

As a constant champion of creative outdoor cooking, it’s something that he was keen to incorporate in his MasterChef dishes: “It was a worry going in [to the programme] that I wouldn’t get to stay long enough to be able to do that. But thankfully I got to bring in a lot of my own cooking.”

Over seven weeks of the competition, between serving up smoked kohlrabi, charring the skin of Arctic char with hot coals and barbecuing one of the nicest pork chops that judge Matt Tebbutt said he had ever eaten, O’Brien managed to leave a bold, smoky stamp on the show.

Known for whole animal cooking, O’Brien is adept at using fire with other ingredients. I still have lip-smacking memories from the Big Grill in 2019 of his whole smoked Irish trout, cooked over fire, and served with an assortment of grilled vegetables. That summer, he also did a busy trade in grilled mussels.

Mark O'Brien is the first Irish chef to be featured on MasterChef

“What I tend to cook a lot at home is fish on the barbecue because it takes barbecue flavour so well. It’s incredibly quick and delicious,” he says.

“I think people can be very nervous about cooking fish on a barbecue, but once you have a couple of nice techniques, it’s very straightforward.”

When planning a barbecue at home, O’Brien believes in looking beyond the obvious focus on meat, instead using grilling, smoking and barbecuing to cook almost any ingredient.

“It’s about taking things that you would normally cook indoors and applying them to the barbecue,” he says.

“The more delicate food takes the grilling and smoking, and that perfume so well. Summer vegetables are incredible, [as are] fish and shellfish. I’ve done shellfish so often at the Big Grill and I just think it’s a hugely under-served barbecue ingredient.”

When it comes to technique, O’Brien has three tips for cooking really good crispy-skinned fish on the barbecue: “Number one is dry skin. Dry off the skin of the fish with kitchen paper and if you can, let it sit open in the fridge for a day or even a couple of hours just to let the skin dry out. Tip number two: A small amount of vegetable oil and salt on the skin, nothing else. No lemon juice, no other seasonings, just oil and salt. And then, the third tip is to use a hot, clean grill. If you do that, you’ll never have a problem with fish skin sticking to the grill again.”

For whole fish, a simple stainless steel fish basket can be helpful: “If you get a whole sea bass, you can stuff it with lemon, herbs, and very fine slivers of garlic, or take it in a more spicy direction, with lemongrass, ginger, and chillies before putting it in the basket. Again, a lot of the same principles — making sure the skin is dry, a small slick of oil and salt on the outside, and making sure the basket is clean and the grill underneath is hot.”

Mark O'Brien: For whole fish, a simple steel basket can be helpful

He likes to make the most of seasonal vegetables: “My personal favourite right now is a charred courgette salad, which is amazing for summer. I’ll take green courgettes, just a little bit of oil and salt on the outside, grill them whole, and I’ll burn the hell out of them. 

“Then I’ll just cut them up really rough into nice big chunks when they’re still warm, dress them with a nice olive oil, salt, maybe a little grated garlic, lemon zest, and some chilli flakes so all of that dressing has a chance to be absorbed into the courgette. I’ll put that on a plate with some whipped feta or whipped silken tofu and add loads of mint and a little bit of chilli flakes to bring a little bit of extra spiciness. It’s the most incredible side dish.”

O’Brien understands the timeless appeal of barbecuing: “It’s such a simple and straightforward method of cooking.

“There’s so much satisfaction in it, and fire itself is fascinating, especially nowadays when everything we do is so safe and so electronic and so removed from the real world. I think barbecue and fire are a great way of connecting people to something authentic that they may be lacking in their day-to-day lives."

Barbecue safely this summer

Trish Twohig, director of Food Safety with safefood.net, shares her top tips: 

1. Think about temperature: barbecue meat should always be cooked to at least 75°C, and if it’s not being eaten straight away, don’t leave it sitting out. Salads, dips and desserts should stay properly chilled (below 5°C). That means keeping them in the fridge until you are ready to serve them or using a cool box with ice packs if you’re outdoors.

2. Keep raw and cooked foods well apart: cross-contamination can happen when bacteria from raw food are transferred to other food. 

Avoid this by:
- Using separate utensils and plates for raw and cooked foods.

- Washing your hands with warm soapy water after handling raw meat, poultry, fish, eggs and unwashed vegetables.
- Keeping foods like salads or coleslaw away from raw ingredients
- Making sure any marinade used on raw meat is not then used as a sauce to coat vegetables or cooked meat. It will contain raw meat bacteria.

3. When it comes to cooking, don’t rely on looks: a nicely charred sausage or burger can still be undercooked in the middle. This is especially important for chicken, pork, minced or skewered meat like burgers, sausages and kebabs. The safest way to check is with a meat thermometer. You’re aiming for at least 75°C at the thickest part.