1 Shake elderflower umbels to remove any impurities. Cut off the stems with kitchen shears.
2 Place the flower umbels in a large bowl and pour in the apple juice.
3 Squeeze out the lime juice, add 3 tablespoons juice to the flowers and gently stir. Cover the bowl tightly with plastic wrap and let soak for 24 hours in the refrigerator, stirring from time to time.
4 The next day: Sterilize 4 jars (250 ml) and lids in a pot of boiling water. Rest jars upside down on a kitchen towel until dry.
5 Toast the almonds in a small dry pan over medium heat until light brown, tossing frequently. Transfer to a plate and set aside.
6 Rest a fine sieve over a pot. Pour the umbels with the juice into the sieve and press with a wooden spoon to extract as much liquid as possible.
7 Add the jam sugar to the strained juice mixture and bring to a boil, stirring to dissolve sugar. Cook, stirring, until mixture thickens, 3-4 minutes more.
8 Stir in the almonds, immediately fill the prepared jars through a funnel and seal securely.
9 Leave the jars upside down for about 5 minutes and then set upright again to cool completely before refrigerating.
Tip: To preserve the jam/sauce for longer, you will need to process the jars according to manufacturer's instructions, or visit http://nchfp.uga.edu/.