Heat 1 tbsp oil in a large pan over a medium heat.
Add the onion and cook for 3 mins, then add the garlic and lemon zest and fry for another 1 min.
Add the pearl barley and the stock. Season, bring to the boil, then simmer for 30 mins, stirring occasionally.
Meanwhile, put the feta in a bowl with the remaining olive oil, half the lemon juice, most of the mint and black pepper. Leave to marinate while the barley cooks.
Remove the lid from the barley and cook for 5 mins more.
Increase the heat then add the peas, half the feta and all the feta juices.
Cook for 3 mins, then check the seasoning.
Serve up and then top each dish with the remaining feta and mint.
