Preheat oven to 190°C. Toss sprouts in 2 Tbsp sunflower oil and place in large dish in oven. Meanwhile, prepare cashews (see below).
After sprouts have roasted for 30 minutes (charred in places, cooked with a bit of a bite), add chilli and garlic. Return to oven for 5 minutes.
Add tamari, stir and return to oven for 10 minutes.
Remove and drizzle toasted sesame oil and more tamari if needed.
For cashews: Stir nuts with 1 Tblsp sunflower oil, syrup and a pinch of salt. Spread out on a baking sheet lined with parchment and toast until golden, ~8 minutes. Check early and take care not to burn them!
Remove to cool, they should become brittle and toffee-like. Break up, combine with cooled, roasted sprouts, and serve.