Retrieve a single recipe by its id. servings rewrites every quantity for that many servings: ranges scale with them, an ingredient with no quantity is left alone, and original still holds the line the source published. Per-serving nutrition does not change, because more servings of the same food is the same plate. units rewrites the recipe in metric or imperial units, converting oven temperatures too and weighing a volume when the density of the ingredient is known; a volume it cannot weigh keeps the unit the source wrote it in and is named in conversion.unweighed. Amounts are rounded once, at the end, the way a cook would write them: grams and millilitres to a step a scale can read, spoons and cups to the fractions they are marked in, and countable things such as cloves to halves.