Cook jasmine rice according to package directions in a rice cooker or on the stovetop (I usually make the serving side for two). Prepare veggies and whisk ingredients together for miso-sesame sauce.
Coat piece of tuna in sesame seeds and season with a bit of salt. Set aside.
Add veggies to a large skillet, cooking over med-high heat with half of the sauce. Add more sauce as needed - I would say I used about 3/4 of it because I don't like a ton of sauce.
Meanwhile, heat olive/coconut oil over high heat in a small skillet. Once oil starts to smoke, add tuna to the pan, cooking for 45 seconds each side (time this on your phone or a kitchen timer). Sear the ends of the tuna for a couple seconds. You basically want to get a good sear on either side and then lightly cook the ends. Remove from heat and cut into thin slices against the grain with a very sharp knife.
Add jasmine rice to each both, then add stir fry veggies. Top with fresh sliced avocado and divide tuna. Garnish with sesame seeds and scallions. Pour reserved sauce (if any) and/or soy sauce overtop of tuna and serve!
Note: I usually have one of these bowls for dinner, and then one for lunch the next day heating up just the veggies and rice then topping with cold tuna and avocado. You can double the recipe to serve more people, but I wouldn't recommend making more than two bowls and eating them both within 24 hours to ensure the tuna tastes its best!