1. Cut the tuna into uniform cubes, brush with evo oil and dip them in white sesame.
2. Blanch each tuna cube 30 seconds per side in a hot nonstick skillet.
3. Prepare a nest of caramelized onion in the center of each plate and surround it with green tomatoes.
4. Place the seared tuna in the center of the nest.
5. Flavor with a grinding of pepper, adjust salt, and serve.