In a medium sauce pan or Dutch oven combine the rinsed brown rice, water, and olive oil. Stir to combine and bring to a boil over high heat. Once boiling cover and reduce heat to low, allow to simmer for 45-50 minutes until tender. Fluff with a fork. Combine the sugar, rice wine vinegar, and salt, pour over the cooked rice and fold in to combine. Set aside until ready to use.
For the Ahi Tuna:
In a shallow dish combine the soy sauce, rice vinegar, and hoisin, stir to combine. Place the ahi tuna steak in the marinade, coating all sides. Allow to marinate while the rice cooks, 40-50 minutes.
After 40-50 minutes or marinating, heat olive oil over medium high heat in a small sauté pan. Once hot, carefully add in the tuna steak. Sear for 2-3 minutes per side, the fish should easily release form the pan when ready to flip. The inside will still be pink, but the outside should have a nice crust. Cook longer if you prefer your fish to be cooked through.
Allow the tuna to rest for 5-10 minutes, then slice into thin strips, against the grain. Have all of the other ingredient's prepared before starting your sushi roll. Start by laying a sheet of Nori, rough side up, on a bamboo sushi mat, layer sushi rice in a thin layer on 2/3rds of the nori. Keeping your fingers wet helps so the rice doesn't stick.
Layer your other ingredients, tuna, mango, avocados, jalapeno, etc. towards the bottom of the nori (see images above). Once you have added desired ingredients/sauces start to roll the nori away from you, using the bamboo mat to help keep things tight. While you roll, continue to pull the opposite end of the bamboo mat until you complete the roll.
Continue with the remaining ingredients, once done slice each roll in half and in half again using a sharp serrated knife. Transfer to a platter and serve with soy sauce or spicy mayo, these are best served immediately.