Place the steak in a bowl and marinate with the ale, 1 stalk of rosemary, the garlic and juniper berries for at least 1 hour.
Drain the steak, keeping the ale and discarding the other bits. Toss the meat with the cornflour.
Heat 2 tablespoons of the oil in a large pan. Brown the meat in batches until golden brown all over. Remove from the pan with a slotted spoon and set aside.
Add 100ml of the ale to the pan along with the onion. Stir and scrape off any bits stuck to the bottom of the pan. Cook for 10 minutes until the onion is softened. Add the mushrooms and carrots to the pan and cook for another 2 minutes.
Return the meat to the pan, along with any juices, and pour in the leftover ale, stock and the chopped rosemary. Bring to the boil, put on a lid and simmer for 2 hours over a low heat. At the end of cooking, stir in the redcurrant jelly, then spoon the mixture into 4 small pie dishes.
Preheat the oven to 200°C, fan 180°C, gas 6. Brush the sheets of filo lightly with the remaining oil. Crumple them up and use to top each pie, then brush with the beaten egg. Bake in the oven for 15 minutes. Serve with rocket leaves.