Mix salsa ingredients and set aside in fridge. I like to allow the salsa to sit for a least 30 minutes and toss occasionally to let the flavors blend.
Cook sushi rice according to instructions.
Mix together sauce ingredients for tuna. Chop tuna and toss in sauce. Place in fridge for 5-10 minutes.
Crush avocado and mush until smooth. Mix with sriracha.
Split sushi rice between two rings; use more or less rice if desired. Place rice in ring mold and top with a thin layer with avocado, keeping in mind 1/8 of an avocado is a safe Fodmap serving size.
Top rice with tuna and salsa. When stacking the tuna and salsa grab the whole pieces and leave the liquid behind.
Carefully remove ring mold. Top with sesame seeds. Serve with gluten-free crackers if desired. I use Absolutely! Grain-free flatbreads (original flavor).