Making Bitter Orange Tart Filling

Our answer

Nigella's Bitter Orange Tart (from SIMPLY NIGELLA) has a ginger-flavoured crust with an orange curd filling that can be made with Seville oranges or a combination of sweet oranges and limes.

If the curd has become grainy then it has been cooked too long or possibly over a high temperature. We suggest cooking it on a low temperature, stirring constantly, and taking the pan off the heat and whisking briefly from time to time to prevent it from over heating. Unfortunately it can take a bit of time and patience. Also avoid using a very heavy-based or cast-iron pan for cooking the filling, as these retain heat and it is much more difficult to prevent the curd from over heating. The recipe also lists soft unsalted butter as this will melt more readily over a low heat. If you have cold butter you may find it easier to melt the butter first over a low heat, take the pan off the heat and let the butter cool slightly before whisking in the remaining ingredients and cooking the curd, again over a low heat.