Seville oranges, also known as sour oranges, or marmalade oranges, are really only available in December, January and February. They make a fine, slightly sour-spicy sauce which balances the richness of a leg of lamb beautifully.

However, if you can't get them, you can reasonably replace them with a combination of regular oranges and lemons, a little heavier on the oranges.

I have gotten to be very fond of gravies made by puréeing the vegetables that have been cooked in the juices of a roast. However, it is important that the roast be a fairly lean one, or the sauce will be too fatty. There should be a thin film over the leg of lamb before it is cooked, but be sure to remove any more substantial quantities, if they are present. It shouldn't be too bad; leg of lamb is usually quite lean.

I have likewise given myself over completely to slow-cooking large pieces of meat. What you lose in the inability to have it rare, you gain in the tender, melting texture. This leg of lamb did not need to be carved; the meat fell from the bone and I just had to pull it apart a bit with the spoon as I lifted it from the pan.

8 servings
7 hours - 1 hour prep time

1  2 to 3 kilo (5 to 7 pounds) leg of lamb
1 large onion
2 medium carrots (2 cups sliced)
1/4 of a large celeriac (2 cups sliced)
1 cup red wine
1 cup beef or lamb stock, or water
the finely grated zest of 2 Seville oranges
OR the finely grated zest of 1 orange AND 1 lemon
the juice of 3 Seville oranges
OR the juice of 2 oranges AND 1 lemon
1 teaspoon allspice berries
2 teaspoons fennel seed
1/4 teaspoon red chile flakes
1 teaspoon salt
2 teaspoons ground ginger
1 tablespoon rubbed oregano

Preheat the oven to 350°F

Put the leg of lamb into a roasting pan, with just enough room around it to add the vegetables. Peel and roughly chop the onion, peel and slice the carrots, and peel and slice the celeriac. Arrange them around the roast. Pour the red wine and stock or water over them.

Grate the orange (or lemon and orange) zest. Juice the oranges (or oranges and lemon) and pour the juice around the roast. Grind the allspice berries and fennel seeds with the chile flakes, and mix them with the grated zests. Mix in the salt, ginger and oregano. Sprinkle the spices over the roast and vegetables.

Roast the lamb for 6 hours. Lift the meat out of the pan into a serving dish and cover it with foil to keep warm as you finish the gravy. It should just fall from the bone; you can pull it apart with a fork and a spoon. Discard the bones carefully - be sure that there are none left in the sauce. Scrape all the broth and vegetables into a blender. Blend until very smooth. Put into a gravy boat and pass with the meat.

- Jennifer Sanders, Seasonal Ontario Food

For more inspiring, local recipes visit Jennifer Sanders' blog, Seasonal Ontario Food.