Place all of the dressing ingredients into a bowl, stir well to combine and set aside.
Bring a large pot of water to the boil. Add a large pinch of salt and cook the pasta as per the packet directions.
Drain the pasta and run it under cold water to cool. Drain well again, then place in a large bowl.
Add the chopped capsicum, carrot, celery and spring onions to the pasta.
Pour over the dressing and stir to combine.
Season with extra salt and pepper if needed.
Set the pasta salad aside for 20 minutes before serving to allow the flavours to develop.
Keep any leftovers stored in an airtight container in the fridge for up to 5 days. For best results, allow the salad to come to room temperature before serving.