Trim the lamb shoulder and cut into 2-3cm cubes.
Peel and finely chop the garlic.
Grate the lemon zest and squeeze the juice.
Put the meat in a bowl and season with salt, pepper, garlic, lemon zest, some lemon juice and oregano. Add 3 tbsp olive oil.
Mix well and allow the meat to marinate for 30 minutes.
Meanwhile peel and slice the carrots. Wash and deseed the peppers and cut into small pieces. Wash the beans and cut into 3cm pieces.
Peel the potatoes and cut into 2cm cubes.
Put the potatoes in a bowl and mix with salt, pepper and 2 tbsp oil.
Preheat the oven to 180°C (160°C fan, gas 4). Divide the feta into 4 equal pieces.
Cut 4 sheets of baking paper.
Spread out the paper sheets on a work surface and place the meat in the middle. Top with the vegetables, potatoes and feta. Season with salt, pepper and oregano and drizzle with olive oil.
Fold the baking paper around the filling to form a packet and tie with kitchen string to secure. Place on a baking tray and bake for 1 1/2 hours.
Remove the packets from the oven, place them on plates and open at the table.