Trim excess fat from the flank. In an air tight container place the flank, sliced garlic, chopped herbs, mustard and pepper corns onto the meat and massage lightly.
Pour the beer over the meat, cover with cling wrap and place the lid on tightly, let marinate for 12 hours, turn once through the process.
Take the flank out of the marinade, pat dry with paper towel, cut into 200g portions, rub some good extra virgin olive oil over the meat and store in the fridge.
Season well with sea salt, Seal the meat for 1 min per side, place on a char grill for 2 min on each side and rest for 8min minimum.(timings will need to be adjusted to suite the grill being used)
Warm the plates, place the Flank back on the grill for 1\2 min to re heat.
Slice the flank across the grain and serve on the mayonnaise, spoon over the chimichurri and finish with red wine jus.
Place the herbs, spices and chili in a food processer and blend. Slowly add the oil in a fine steam and continue to blend until smooth (add a bit more oil if needed just until all the ingredients start to move around in the mixer).
Fold in the red wine vinegar and season with sea salt and store in a air tight container in the fridge (will last 1 week).