Thermomix Method:

1. Place onion into TM bowl and chop 3 sec/speed 5. Remove to a bowl and set aside.
2. Place herbs into TM bowl and chop 7 sec/speed 7. Scrape down sides of bowl, and chop again  1 sec/speed 7 if needed. Remove to bowl with onions. Rinse and dry TM bowl.
3. Place almonds into TM bowl and chop 7 sec/speed 5.
4. Add sumac, cayenne, 1/2 tsp salt (or to taste) and olive oil, and mix 10 sec/speed 3. Return onion and herb mixture to TM bowl and mix 10 sec/speed 3. Place mixture back in bowl, cover and place in fridge until fish is done. Rinse and dry TM bowl.
5. Place tahini, lemon juice, 1/2 tsp salt (or to taste) and water in TM bowl and mix 10 sec/speed 4, or until smooth. Consistency should be like thick cream. If it looks like the tahini has curdled, add water a bit at a time until it reaches desired consistency. Remove tahini mixture to a bowl, cover, and refrigerate while fish cooks. Rinse out TM bowl.
6. Weigh 500g water into TM bowl and place Varoma into position on lid. Divide fish fillets between the Varoma dish and tray, spacing to leave plenty of room for air flow. (If some of the fillets are thicker than others, place them in the dish as they will cook quicker in dish than on tray.) Cook for 18 mins/Varoma/speed 2 for smaller fillets, or increase the time to 20-25 mins/Varoma/speed 2 for larger fillets.
7. Check fish to see if it is cooked. You will know it is done if it has turned from translucent to opaque inside – use the tip of a small knife to peek at the inside of the fish. The flesh should easily give way. Don’t cook it until it flakes apart as fish will continue to cook for a few minutes after you stop cooking, and flaky fish will be too dry once cooled. If it needs more cooking time, just give it 3 mins/Varoma/speed 2 and recheck. Remove fish from Varoma onto a large serving platter.
8. If serving warm, spread the tahini mixture evenly over the fillets, then add the herb and nut mix on top of that. Press down gently, so the herb and nut mixture sticks to the tahini mixture. 
9. If serving cold, refrigerate fish and toppings separately and assemble just before serving.
10. Store in an airtight container in the fridge for up to 3 days.