Making fruit curd

Perfect fruit curd requires gentle heat and constant stirring to prevent curdling while achieving proper thickness. Use medium-low heat and whisk continuously - mixture should coat spoon at 170°F. Strain immediately through fine sieve to remove any lumps and zest pieces for silky smooth texture. Whisk in butter gradually off heat to create glossy finish and prevent breaking. The curd should hold its shape when spooned but remain spreadable. Press plastic wrap directly onto surface to prevent skin forming during chilling. 

There is a fairly reliable formula for fruit curds. The classic ratio is approximately:

Basic Curd Formula (per 1/2 cup fruit juice):

• 1/2 cup fruit juice

• 1/2 to 2/3 cup sugar (depending on fruit acidity)

• 3-4 egg yolks

• 4-6 tablespoons butter

Key variables by fruit type:

• Lemon/lime: Higher acid, needs more sugar (2/3 cup)

• Orange: Medium acid, moderate sugar (1/2 cup)

• Passion fruit: Very tart, needs more sugar

• Berry curds: Often need less sugar due to natural sweetness

Butter is almost always added last and off the heat. This prevents the emulsion from breaking due to temperature shock. The technique is:

1. Cook juice + sugar + yolks to 170°F while stirring constantly

2. Strain immediately to remove lumps

3. Then whisk in cold butter pieces gradually off heat

Why this order matters: Adding butter to the hot mixture while still on heat can cause the proteins to seize and the fat to separate. The residual heat from the cooked curd is sufficient to melt the butter while maintaining the smooth emulsion.

Consistency check: Properly made curd should coat a spoon but still be pourable when warm, then set to spreadable consistency when chilled.

This formula scales reliably - just maintain the ratios and always finish with the butter off heat.