1.Heat oil in a 6-litre (24-cup) pressure cooker; cook chicken, in batches, until browned. Remove from cooker.
2.Melt half the butter in cooker; cook leek and garlic, stirring, until leek softens. Return chicken to cooker with verjuice, stock and sage; secure lid. Bring cooker to high pressure. Reduce heat to stabilise pressure; cook 10 minutes.
3.Release pressure using the quick release method; remove lid. Add parsnip and pear; secure lid. Bring cooker to high pressure. Reduce heat to stabilise pressure; cook 5 minutes.
4.Meanwhile, melt remaining butter in small frying pan over high heat; cook extra sage leaves until bright green and crisp. Drain on absorbent paper.
5.Release pressure using the quick release method; remove lid. Season to taste. Serve stew sprinkled with crisp sage leaves.
If you have an electric pressure cooker you won’t need to reduce the heat to stabilise pressure, your cooker will automatically stabilise itself. Always check the manufacturer’s instructions before using. Make sure you use firm pears or they will become mushy. Store crisp sage leaves in an airtight container for up to 2 days. The stew is suitable to freeze. Quick release method: Each time the lid is removed from the cooker, the pressure must be released quickly first. Use tongs (steam can burn your fingers) to turn the pressure valve on top of the cooker to open the valve and release the steam. We use this method when adding ingredients and when checking the food toward the end of cooking time.