Place the barley in a medium pot with the salt and lemon zest. Bring to a boil. Reduce the heat and simmer, covered, for 60 minutes. Remove the lemon zest. Add the currants and simmer for another 15 minutes, adding a little more water if needed, until the barley is soft. Stir in the sugar and cream.: As the pot comes to a simmer you ll notice a warm, grainy perfume rising, and the surface will begin to show gentle bubbles, not a violent roar. Low and steady heat produces even cooking, so you want a soft, continuous simmer, not a hard boil. The barley will move from opaque to translucent at the edges as it hydrates, and you ll see the grains swell and plump. Covering the pot traps steam, which helps soften the barley evenly, and stirring occasionally prevents the bottom from catching. After about forty minutes you may need to lift the lid and stir, checking texture, and add a little extra water if the pot looks dry. When you remove the two strips of lemon zest , the broth will smell subtly brighter; take care to pull them out so their bitter white pith does not tint the pudding. When you add the currants , you ll see them swell and release little pockets of sweetness into the liquid, darkening the mixture slightly. Stirring in the cane sugar dissolves quickly, smoothing the flavor, and the final swirl of heavy cream will turn the cooking liquid into a glossy, gently thickened sauce. A common mistake here is rushing the simmer with too high heat, which can toughen the grains and evaporate the liquid too fast.
