Place onion, garlic and gherkin into TM bowl. Chop 2 sec/speed 6.
Add remaining ingredients, except grapeseed oil and set timer for 4 min/37°C/speed 4.
When there is 3 minutes left on timer, hold MC in place with your hand, (to prevent it floating) while you pour the oil onto the lid.
If it doesn't emulsify completely like a mayonnaise, don't worry, it'll set more in the fridge.