Mix all the dry ingredients well and put them into a large crockery or other non-metallic container. Stir in the water, then add the onion, garlic, and lemon.Add the meat, which should be submerged. It may help to put a plate bottom-down on top of the meat, then weight the plate. Put the container in a cool place for 15 days, turning the meat every day or two.
When you are ready, rinse the meat and cook it by any corned beef recipe.