Preheat the oven to 220°C (430°F/430/gas 8).
Peel the outer layer of the sprouts and give them a good wash. Bring a large saucepan of salted water to the boil, add the sprouts and parboil for 10 minutes until semi-soft. Careful the sprouts don’t turn a dull green which means they have been overcooked. Drain well.
Line a large baking tray (pan) with baking parchment, then spread the Brussels sprouts over the parchment. Make sure the sprouts have enough space in between and flatten them with the palm of your hand or the bottom of a drinking glass until they are as flat as possible. You might find that some water comes out of the sprouts when you flatten them, so soak up any excess water with paper towel.
Drizzle the sprouts with olive oil and a generous sprinkling of salt and sesame seeds, then pop in the oven for 10–15 minutes until brown.
Remove the tray from the oven, turn the sprouts, sprinkle with more sesame seeds and pop back in the oven for a further 10 minutes. You want the sprouts to be golden and crispy!
While the sprouts are cooking, mix all the ingredients for the mayonnaise together in a bowl and set aside.
Once the sprouts are golden, remove from the oven and eat immediately while they are super crispy, dipping them in the garlic mayo.