Peel and finely dice your onion. Get a large pot hot. Add a gloss of oil. Stir the onion in. Season. Lower heat. Sizzle till softened, about 5 mins.
Peel and chop your garlic. Peel and finely grate or chop 1 tbsp ginger. Stir into the onion.
Rinse and finely chop your broccoli. Add it to the pan along with enough of the boiling water or stock to cover. Simmer till the broccoli is tender.
Grate the zest of the lemon into the bowl of a food processor or blender. Add the leaves from your mint (save a few to garnish) and the flesh from your avocado. Blitz till you have a smooth paste. Add a pinch of salt, pepper and a little olive oil or water, if it need loosening.
When your broccoli is just tender, add it slowly (along with the water/stock, onion, ginger, etc.), blending as you add, till you have a smooth soup.
Taste. Add more ginger or seasoning to your liking. Garnish with the reserved mint leaves.
*Your avocado needs to be ripe for this soup. If you squeeze it and it gives a little, it should be perfectly ripe. To help soften it, pop it in a paper bag (adding a banana to the bag will help ripen it even faster).