Jam as we know it is typically made from roughly equal weights of fruit and sugar, with naturally occurring pectin in the fruit being released by long boiling so that it can “set” the jam into a gel. The high proportion of sugar acts as a preservative, allowing us to keep jam sealed in sterilised jars at room temperature for months or years.
This recipe, from Tom Pountney, harks back to the centuries before a cheap supply of sugar from the West Indies led to widespread production—in homes and commercially—of what we now call jam. Until the 19th century, sugar was too expensive for all but the well-to-do to buy in large quantities. Preserves were often made instead with honey.
Tom’s jam relies on the natural sweetness of strawberries lifted with a little raw honey or unrefined sugar. Because the fruit is cooked in the Thermomix for a relatively short time, pectin cannot be relied on for setting and so agar-agar (or alternatively, gelatine) is used to produce a jammy texture. The low sugar levels in this jam are good news for those of us trying to minimise the sweet stuff but they will not preserve it at room temperature—hence the need for refrigeration from day one.