Heat the oven to 200c/fan 180c/gas 6. Line 6 tart tins (about 10cm across) with pastry and prick the bases.
Line with parchment and baking beans and bake for 10 minutes or until the pastry starts to brown, lift out the parchment and bake for another 5 minutes or until the pastry is crisp, dried and cooked.
STEP 2
Meanwhile, slice the red onion thickly (you need 6 fat slices). Heat a little oil in a large frying pan (you may need to use 2 pans, or do it in 2 batches) and carefully fry the slices, without breaking them, on each side until they start to soften, about 15 minutes in total.
Add the balsamic and thyme and bubble together.
STEP 3
Lift a slice of onion into each tart and put a slice of goat’s cheese on top, against one side of the pastry so it is off centre.
STEP 4
Bake until the goat’s cheese begins to bubble and brown a little. Drizzle with a little olive oil before serving.