Add the oil to a medium-sized saucepan (see Kitchen Notes below).
Cook the onion and garlic with a pinch of sea salt over medium heat for about 5 minutes until they have softened.
Add the cherry tomatoes, sugar, vinegar, sea salt and pepper.
Mix well.
Turn the heat up to high and let the mixture come to a boil.
Keep cooking at high heat for about 15-30 minutes, or until the mixture has thickened and looks jammy. The tomatoes will release some liquid during cooking, and the mixture will start to thicken once the liquid evaporates.
During this time, gently break down any tomatoes with a wooden spoon and stir the mixture from to time to prevent it from sticking to the bottom of the pan.
Once the mixture has thickened, taste for seasoning. You may want to add some more sugar or more vinegar.
Serve the tomato relish warm, or spoon the mixture into a warm sterilised jar and seal.
Kitchen Notes
RIGHT SIZED SAUCEPAN Make sure your pan is only half-full with all of the ingredients so that there is room for the mixture to bubble away and boil. Otherwise, the mixture is likely to overflow.
RECIPE CREDIT Recipe adapted from Donna Hay Magazine, Issue 41, Oct/Nov 2008.
VARIATIONS This cherry tomato relish is delicious as it is but, as you will read in the comments below, many readers have added other flavourings with much success. Suggestions include chillies, mustard seeds, fennel seeds, Worcestershire sauce ... I love to add some chipotle chile powder for a bit of a kick.
STORAGE TIPS This cherry tomato relish keeps well in the fridge for at least a couple of weeks.
OVEN & STOVE TEMPERATURES All recipes on this website have been tested on an induction stove and/or with a conventional oven (i.e. an oven without fan). All recipes on this website use temperatures for a conventional oven, unless otherwise mentioned. Convection ovens (i.e. fan-forced ovens) are typically 20°C/70°F hotter than conventional ovens, but please check your manufacturer’s handbook.