Using a very sharp knife, delicately cut the tuna into small 1/2 inch cubes. Place into a large bowl and add in the soy sauce and sambal. Toss to coat and allow to sit for 5-10 minutes to marinate.
In the meantime, prep the sriracha mayo by mixing equal parts sriracha and mayo. We found about 1 tablespoon of each was plenty of sauce for the two of us. Set aside.
Chop the cucumber and avocado into cubes as well and toss into bowl with tuna. Toss to coat, once again.
Top with sesame seeds, cilantro, and sriracha mayo. Serve with your choice of base such as mixed greens, brown rice or cauliflower rice.
