For the healthiest version of this soup, make it a day ahead to skim the fat off before reheating and serving.
Heat oil in pressure cooker. Cook onion until soft.
Add lamb and seal on all sides.
Pour in chicken stock until meat is covered
Add remaining herbs, vegetables, and barley
Simmer with lid on until meat is tender and begins to fall off the bone
Season to taste with iodised salt and cracked pepper