1.Cut stems from artichokes. Snap off tough outer leaves until you are left with a central cone of leaves.
2.Trim away any dark green parts; cut away top of cones. Rub artichokes all over with a lemon half. Place artichokes in large glass or china bowl with another lemon half; cover well with water.
3.Heat combined garlic, peppercorns, vinegar and the water in large non-reactive saucepan until hot; do not boil. Add drained artichokes and remaining lemons; simmer, uncovered, 15 minutes or until chokes are easy to remove from centres. Drain; cool 5 minutes.
4.Remove and discard centre leaves and chokes using a small spoon. Cut artichoke hearts in half; place hearts in sterilised 1-litre (4-cup) jar. Top with enough oil to cover, taking care as it will bubble. Leave 1cm space between hearts and top of jar; seal while hot. Refrigerate 1 week before using.
Recipe can be made 3 months ahead and refrigerated.Note