Fill a saucepan with water and 1 tsp of salt and bring to boil.
Drop in the artichokes, bring back to boil, then lower the heat right down and simmer for 15 minutes, until the artichokes are just cooked. Drain and set aside.
Heat a large frying pan on high heat with 2 tablespoons of the olive oil.
When the oil is very hot and almost smoking, drop the artichokes in and sauté them for about 2 - 3 minutes on high heat, tossing frequently, until they are lightly charred at the edges.
Take off the heat but leave the artichokes in the pan.
In the meantime, heat the olive oil and vinegar separately in 2 saucepans until just simmering, and turn the heat off.
Get your sterilised jar and place the remaining salt, chilli flakes and rosemary in it.
Follow this with the artichokes, packing them in.
Top with the hot vinegar.
Finally, pour the hot olive oil in, making sure that the artichokes are fully covered.
Cover, give it a shake to mix it all up, then leave to cool to room temperature.
Store in the fridge for at least 24 hours to allow the artichokes to absorb the flavours.
Will keep in the fridge for 7 - 10 days.
Notes
Total time doesn't include the minimum recommended marinating time of 24 hours.