Combine tomatoes, sugar, basil, onion, lemon juice, vinegar, salt, black pepper, coriander and cumin in a medium saucepan over medium heat. Bring to the boil, stirring occasionally.
Reduce heat to low and simmer, stirring occasionally, until thickened and reduced by half, 2 to 3 hours. Remove from heat.
Divide jam between 2 sterilised jars. Allow to cool slightly before covering with sterilised lids. Refrigerate jam for up to 2 weeks or freeze for up to 4 months.
Note:
The amount of sugar should be adjusted depending how sweet your tomatoes are. Simmering time may vary depending upon the moisture content within your particular tomatoes.