Combine all the patty ingredients in a ziplock bag, massage thoroughly to combine, press air and seal. Allow to marinade at room temp for at least 30 mins
Combine all the chimichurri ingredients in a small food processor, or a cup slightly larger than your emulsion blender and pulse just a couple times to combine and chop
Split the meat into 3 equally sized balls
Heat a skillet on medium heat until water droplets sizzle on it.
Toast all the buns and set aside.
Lightly press each patty into the pan, not so much to smash, but enough to form a patty slightly wider than your buns, probably around 1" thick. Cook 2 minutes, flip add halloumi, cover and cook another 2 minutes covered or until the cheese melts.
Form the burgers- fresh parsley on the bottom, patty, onions. Yogurt and chimichurri on the top. Consider cutting in half to eat.