Preheat the oven to 170, wash the beetroots, dice and place them onto a sheet of foil on a baking tray. Drizzle with olive oil, season with salt and pepper and add two cloves of peeled garlic, the balsamic vinegar, marmalade and wrap them to cover. Cook them for an hour and then allow to cool.
Place all the ingredients along with the walnuts into a food processor and blend until combined and to how you like it; I tend to leave it a little chunky. Set this aside, and this makes a fantastic dip as well.
These are smaller burgers, that should just fit into your hand so I usually take an 8cm cookie cutter and cut around the bun creating a smaller burger. Use the left over bread for the bread crumbs and blend them until fine.
Tip this into a large bowl, mince or finely dice the onion and add this to the crumbs, squeeze in the garlic, add the herbs and lamb mince and squeeze to combine, season with salt and pepper.
Wipe over the mushrooms and slice off a small amount from the mushroom cap so that they sit flat. Chop up the caps and add this to the lamb mix.
Take a good sized amount of the minced lamb – about ¼ cup or slightly smaller and squeeze and mold this into the mushroom where the stalk is. Once you have filled all the mushrooms sit them cap side down so they sit flat and place in the fridge for at least 20 minutes.
Heat a pan or barbeque and drizzle on a small amount of oil, place the mushroom down into the pan with the mince facing upwards and cook for 3-4 minutes until golden, turn over and cook for 4-5 minutes. Cook the haloumi until golden and on each side then assemble the burgers with some of the beetroot relish, the burger, slice of haloumi, sliced red onion, leaves and top.