The origins of this recipe are the weekly bounty from my farm share and a seasonal, farm-to-table recipe from Jamie Oliver's Jamie at Home book, which you can also find in American and English versions online. This is a self-sustaining, self-sufficient meal where each dish contributes to another: a quick compound butter with grated radish makes a wholesome appetizer while you're finishing up the cooking; and you can use the radish tops and turnip greens to make another veggie dish for the table, flavored with a spoonful of the rendered fat combined with the juices of your slowly roasting lamb. You also have tons of leftover opportunities: make lamb stock, mix up leftover lamb and gravy (and some leftover cooked carrots and peas if you have them) and serve over polenta, use the rendered fat to make wonderful everything from scrambled eggs to saag paneer and dal (as long as you're not serving vegetarians).
For the lamb:
One 3.5-lb lamb shoulder (or more or less, depending on the number of mouths you have to feed)
A whole bunch--or two--of fresh herbs (or just rosemary for strong, consistent flavor)
For the compound butter:
2 sticks of butter, at room temperature
One small bunch of radishes (save the tops)
A few big handfuls of fresh herbs (anything you have on hand, maybe the same as what you used for the lamb, but cilantro is great, too)
Dense rye bread and cornichons, for serving
For the golden mash (increase, decrease, or swap ingredients, depending on what your have):
2 medium Yukon gold potatoes
2 large yellow carrots
1 small bunch Tokyo turnips (save the greens)
Up to half a stick of butter
Up to half a cup of milk
For the greens:
Radish tops (reseved)
Turnip greens (reserved)
For the gravy:
1 tablespoon flour
2 cups chicken or lamb stock (think ahead and turn the roasted bone from this recipe into stock for the next time), at room temperature
2 tablespoons capers (I prefer the kind in brine rather than packed in salt), rinsed and chopped
A handful of chopped herbs
2 tablespoons red wine vinegar
Salt and pepper, for everything
Take the lamb out of the fridge before your do anything else so that it can come to room temperature. Preheat the oven to 500F and have a reliable roasting pan (with or without a rack--I like using the rack) ready.
Chop all of your herbs (for the lamb and the butter), keeping different ones separate or mixing them all together.
Using a sharp knife make little incisions all over the surface of the lamb (this is Jamie Oliver's instruction--maybe it's to help get the flavor in?). Place the lamb (on the rack) in the roasting pan and generously glug some olive oil over the top. Sprinkle with salt and pepper just as generously. Dump at least a cup of chopped herbs on top. Now use your hands to smear everything around and cover the lamb on all sides and corners. (This is all really about feel. If making a dish like this for the very first time, get ready for the trial and error. Here are some benchmarks: ultimately the lamb should be coated but not swimming in oil, and two teaspoons of salt and a teaspoon of pepper are probably enough.)
Cover the roasting pan tightly with foil and place it in the hot oven. Bring the temperature down to 325F right away and get ready for the meat to cook for a very long time, until it's falling off the bone. Mine took a full five hours. This depends on the size and weight of your roast, and probably a few other things.
You might prepare the compound butter now and then take a break and come back closer to dinner time. Grate enough radishes to fill half a cup. (Save the rest of the radishes to eat later.) Dump the butter, the grated radish, half a cup of chopped herbs, and salt and pepper to taste (the amount depends on whether your butter is already salted) in a mixing bowl. Use a rubber or silicone spatula to combine everything thoroughly. Scrape the radish-herb butter into a couple of ramekins. Cover and refrigerate, but remove from the fridge about a half hour before serving. When you're ready, serve the compound butter with small pieces of rye bread (you can toast the bread but I like it when both bread and butter are room temperature), the cornichons, and the leftover radishes. This is a great finish-up-cooking snack, especially if you've invited friends into the kitchen for a glass of wine.
When you think you have about an hour to go with the lamb, bring a large pot of salted water to boil (this is for the veggies that you will ultimately mash) and find another good medium pot with a lid (set that one aside for the greens).
Scrub and roughly chop all the veggies for the mash (no need to peel anything--and leave the naturally little turnips whole if they're no bigger than a large strawberry). When the water is at or close to boiling, drop in the veggies. Keep at a medium boil until everything is soft, maybe half an hour. You don't have to be a perfectionist--the cooked veg should be mashable but not disintegrating. Scoop out about half a cup of the water from the pot. Drain the veg and place it in a mixing bowl. Use a potato masher (or just a couple of wooden spoons) to mash, leaving some chunks in the mix. Using trial and error, add butter, reserved starchy hot water, milk, and salt and pepper until you have the taste and texture that you want.
Spin the greens in a salad spinner. Then drop them in the pot with just the residual water clinging to them. Cover the pot and heat on low, stirring occasionally until the greens are wilted. When they're almost ready, stir in a tablespoon of the wonderful stuff collecting in the bottom of the roasting pan (an herby combination of olive oil, rendered fat, and juices from the lamb) and some salt. Taste and add some more of either if you'd like.
When the lamb is ready, remove the roasting pan from the oven and place the lamb shoulder on a wooden board. Cover loosely with foil and leave it to rest for at least ten minutes.
Pour off all but about a tablespoon of fat from the pan and save it for another use. If the roasting pan can go on the stove, make the gravy directly in the pan. Otherwise, pour what's left in the roasting pan into a small pot. Place over medium heat and stir in the flour until you have a smooth paste. Pour in the stock, stirring as you go, and then the capers. Let the gravy simmer and thicken for maybe five minutes (though it won't be especially thick). Stir in the herbs and the vinegar.
Serve everything at once.