1. Place a mesh strainer and a medium bowl close at hand near your stove.

2. Place the sugar and butter in a food processor and process until smooth.

3. With the processor running, add the eggs one at a time, followed by the passion fruit concentrate and the salt.

4. Pour the mixture into a small saucepan and cook very slowly over a low heat, stirring constantly, until slightly thickened (about 10 minutes). Do not allow the custard to boil. To check the consistency, lift your stirring spoon from the mixture and swipe a finger across its back; if your finger leaves a clear path on the spoon, the curd is ready to come off the heat.

5. Immediately remove the curd from the heat and strain it into a clean bowl.

6. Set aside to cool to room temperature.

7. Refrigerate for 5–7 hours, until well chilled. Curd keeps in the refrigerator for several weeks