Divide the minced chuck steak into 4 and, with wet hands, roll each piece into a ball, then press into flat patties roughly 2cm wider than your buns. Place on an oiled plate and place in the fridge to firm up.
Preheat the barbecue to high or place a griddle pan over a high heat until screaming hot.
To make the slaw, add the yoghurt and both mustards to a large bowl and squeeze in the lemon juice. Pour in the extra virgin olive oil and season with a pinch of sea salt and black pepper, then mix together well.
Remove the tatty outer leaves from the cabbages and peel the onion and carrot. Coarsely grate all the veg into the bowl of dressing, along with the apple.
Pick the mint leaves and finely slice them with the chilli (deseed if you like), gherkins and spinach, then add to the bowl and set aside to toss together just before serving.
Season the burgers with a small pinch of salt and pepper and the cumin seeds, then place onto the barbecue or griddle pan.
Cook the burgers for 3 to 4 minutes, then flip them over. Place a slice of cheese on top of each one and cook for a further 3 to 4 minutes, or until the cheese has melted and the burgers are cooked to your liking.
Meanwhile, cook the bacon until sizzling and golden brown all over, then remove to kitchen paper to drain.
Once cool enough to handle, chop the bacon into small pieces, add to the slaw, then mix everything together. Have a taste and add a little more lemon juice or seasoning, if needed.
Cut the burger buns in half and lightly toast them, cut-side down.
Spread a little tomato ketchup onto each base and place a burger on top. Add a dollop of slaw and the bun tops, then – this is the most important bit – press down to squash all those delicious flavours together, and tuck in!