• In a small mixing bowl, sift together your flour, baking powder, baking soda and salt.
• Cut your rhubarb into lengths that will fit nicely in the bottom of a 1 liter or 4 ¼ cups pudding basin or metal mixing bowl.
• Butter the basin and then add the rhubarb, curved side down. Drizzle over the golden syrup.
• Beat the sugar and butter together until they turn light yellow and fluffy.
• Add in the eggs, one at a time, beating well between each addition.
• Beat in the lemon zest and vanilla.
• Sift in the flour mixture and add the milk. Fold them both in.
• Spoon the batter into your pudding basin.
• Cover the basin with parchment paper, folding it over in the middle to allow room for expansion, and secure it with kitchen string.
• Before you cut the ends of the string, tie them to create a handle with which to lift the basin and trim excess parchment.
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• Put the covered basin in a large pot and pour hot water into the pot till it comes two-thirds of the way up the basin.
• Bring the water to a gentle boil then cover the pot and lower the flame to simmer.
• Simmer for 1 ½ hours.
• Once the steaming time is up, remove the basin from the pot.
• Leave to cool for five minutes, then run a knife around the edges of the sponge pudding.
• Turn out on a serving dish.
• Cut into wedges and serve with optional rhubarb sauce and pouring cream.

The Rhubarb Sauce

• If you are making the optional rhubarb sauce, you've got plenty of time while the pudding steams.
• Put all the sauce ingredients into a small pot.
• Cook for about 10 minutes, until the rhubarb has softened. Taste the sauce and add a little more sugar, if necessary.
• Cook till you reach a nice spoonable consistency, perhaps another 5 minutes.