2) For the compote, heat the olive oil in a very large skillet over medium heat. Once the oil is shimmering (not smoking), add the onions and a pinch of salt, and stir to coat with oil. Cover and reduce the heat to low. Cook, stirring occasionally, until the onions turn a deep caramel colour, about 45 minutes.
3) Warm your griddle or griddle pan over medium heat.
4) When the onions are caramelised, add the dates, vinegar and water. Stir and cook, covered, for another 15 minutes.
5) Fold a paper towel in four, pour a little vegetable onto it and wipe down your griddle pan.
6) Once the griddle pan is nice and hot (oil lightly smoking), throw your rubbed meat on. It should sizzle upon contact; if it doesn't, your pan wasn't hot enough. This is how you ensure a nice crust on the steak! After 5 minutes on one side, flip the steak over, and cook another 4-5 minutes. Check the temperature; I like my skirt steak done medium-rare, so I pull it off as soon as the thermometer register 50C. Pull onto a chopping board and tent with foil; allow your meat to rest for 5 minutes.
7) Slice the steak thinly against the grain on the bias; if you don't, your precious steak won't be incredibly tender and will be deeply unsatisfying! Serve with a dollop of onion compote on top.