Steps
- Heat 1½ tablespoons of olive oil in a skillet over medium heat. Cook 1 very finely chopped onion with salt for 15 minutes, then add 70g of finely chopped smoked pancetta and cook for 5 minutes.
- Add 1 crushed garlic clove and the leaves of 4 thyme sprigs; cook for 2 minutes, then cool for 15 minutes.
- Knead 500g of lean ground beef for 5 minutes. Mix in the onion mixture, 50g of fresh breadcrumbs, and 1 egg yolk; season and shape into four 4in / 10cm patties.
- Mix 60g of grated sharp cheddar and 60g of grated mozzarella, then form four 1½in / 4cm disks. Enclose a cheese disk in each patty, seal firmly, flatten slightly, and chill for 30 minutes.
- Blend 120g of mayonnaise, 2½ teaspoons of English mustard, ½ small bunch of chopped parsley, and ½ small bunch of basil. Stir in 50g of finely chopped small dill pickles.
- Heat a charcoal barbecue until the flames subside and the coals are ashen. Cook the patties for 4-5 minutes per side, then wrap each in foil and cook for 5-7 minutes, until the beef reaches 160°F / 71°C and the cheese melts.
- Toast the cut sides of 4 seeded burger buns for 1-2 minutes. Spread with the sauce and fill with patties, the leaves of 2 Little Gem lettuces, and 2 sliced ripe tomatoes; finish with crispy fried onions.