Preheat oven to 180°C.
In a large pot, add the quinoa, Knorr Vegetable Stock Pot and water. Bring to the boil over high heat, then simmer gently for 10 minutes, until quinoa is tender. Remove from heat, separate by mixing gently with a fork and leave to cool slightly.
Mix together the feta, parsley, garlic, lemon juice, lemon zest, quinoa, and half of the oil together in a large bowl. Stuff the peppers with the mixture and drizzle with remaining oil.
Bake for 20 minutes, until the peppers have softened and the stuffing is crispy golden brown.