TO PREPARE THE HALLOUMI
Cut each block of halloumi in half horizontally through the middle to create 4 flat halloumi steaks in total.
FOR THE UMAMI BUTTER
Mix all the ingredients together in a bowl, seasoning with a good pinch each of salt and pepper.
SETTING UP YOUR EGG
Set up your EGG for direct cooking with the Cast Iron Searing Grid. Your target temperature is 200˚C.
Brush the portobello mushrooms on one side with the umami butter and place them buttered side down on your Cast Iron Searing Grid. Brush the other side thickly with butter while they are cooking. Turn the mushrooms over after 2–3 minutes and add the halloumi to the barbecue. Brush the surface of the halloumi with umami butter too. Keep brushing the mushrooms with the butter as they cook; do the same with the halloumi.
Towards the end of cooking, toast the burger buns on the EGG. Brush any leftover butter onto the toasted buns.
To assemble the burgers, place a mushroom on the base of each burger bun. Top with a halloumi steak and add a spoonful of sweet chilli or hot chilli sauce. Pile a big handful of rocket on top. Spread some mayo on the burger bun lids and sandwich together. Tuck in straight away.
Use a coffee grinder to grind dried mushrooms. Keep in a sealed jar to add flavour to other dishes, such as pasta sauces, soups and stews.
Extracted from Tom Kerridge’s Outdoor Cooking: The Ultimate Modern BBQ Bible, published by Bloomsbury