ROASTED ONION “STEAK”
Step 1: The Steak
Preheat the oven to 250°C. Toss the onion with the olive oil, sea salt and black pepper in aluminum foil, place on an oven tray. Cook for 35 minutes, once done, portion the onion steaks (2-inch tall slices) and reserve.
For the “steak”
Step 2: The Caramelized Onion Purée
Slice the onion very thin. Preheat a pan with the vegetable oil and add the onion. Once the onion is starting to caramelize, add the butter and salt. Cook until dark brown and caramelized. Blend until smooth and reserve.
For the caramelized onion purée
Step 3: The Demi-glace
Slice the onions and shallots very thin. Roast them in the oven with the tomato paste while you’re cooking the onion steak. Once they're almost charred, place them in a sauce pan and add the red wine. Reduce almost halfway and add the vegetable stock. Reduce again until half the liquid is gone and add the vinegars. Reduce halfway and reserve. You should now have a caramelized sauce.
Step 4: Plating
Place the caramelized onion purée on the bottom of a deep plate, top with one 2-inch tall onion “steak”, cover in demi-glace and finish with cotija cheese.
For the demi-glace