Use a mandolin to finely slice the courgettes lengthways into long ribbons and place them in a bowl with the 3 tbsp of olive oil.
Swish them around in the oil to coat them and season with salt and pepper.
Heat a griddle pan and toast the courgette ribbons for approximately 2 minutes each side.
Have the lemon juice ready in a bowl and toss the cooked courgette ribbons in the juice.
Set them aside to cool.
Finely slice the garlic and layer this in a sterilised jar along with the courgettes ribbons and the thyme leaves.
Top up the jar with olive oil.
Using a skewer prod around the jar to release any air bubbles and tap it on the table top too.
Make sure the courgettes are completely covered in the oil and pop on a lid.
Use within one month and store in the fridge.