Combine all aioli ingredients in a blender. Blend until smooth and creamy. Let rest in the fridge for 30 minutes before serving. Aioli can be made ahead of time. Prepare rice according to the instructions on the package.
Season tuna all over with salt and pepper. Place sesame seeds on a plate and mix to combine. Press filets into the seeds until completely covered. If it's easier, you can also sprinkle filets all over with sesame seeds. I like to liberally cover.
Heat oil in a cast-iron skillet or pan over medium-high heat. Let the pan become hot before proceeding. Place filets face down and sear for 90 seconds. Flip and sear for an additional 90 seconds. For tuna that is pink in the center and more cooked through, sear for 2-3 minutes per side. Remove from the heat and set on a cutting board to rest for 3 minutes before slicing.
Slice filets against the natural grain and serve over rice drizzled with soy sauce and aioli. Garnish with jalapeno slices and lime wedges.
