Mix together the oil, lemon juice, garlic and thyme in a shallow non-metallic dish. Season with salt and pepper Add the lamb steaks and turn over so that they are covered in the marinade
Cover and allow the lamb to marinate for at least 1 hour or for up to 24 hours in the refrigerator.
To make the mash
Heat the oil for the mash in a saucepan and gently sauté the onion for 5 minutes until soft, add the garlic and cook for 1 minute. Add the butter and milk. Stir in the beans and heat gently stirring occasionally while you cook the lamb.
Remove the lamb from the marinade and cook under preheated grill or on a ridged griddle pan for 3–4 minutes each side. Transfer to a warm plate and allow to rest for a minute or two.
When the beans are piping hot, Season with salt and pepper. Remove from the heat and mash with a potato masher. Spoon onto serving plates and place the lamb on top, spooning any juices that have come from the meat during resting.
Garnish with a few thyme sprigs and serve.
Nutrition information is calculated using an online nutrition database - is approximate and is meant as a guideline only. (It does not include seasoning with salt and pepper.)