Dice the bell pepper and thinly slice the scallion and garlic. Heat two tablespoons of olive oil in a large skillet over a low/medium heat. Add the bell pepper, garlic, and half the scallion. Sweat gently for a minute or two until tender and fragrant.
Drain the tuna and flake into the skillet with the bell pepper. Add the cauliflower rice, sesame oil, and tamari sauce. Stir well to combine. Cook over a medium heat for 2-3 minutes to heat the rice and tuna through.
While the rice mix is cooking, crack the eggs into a bowl. Season with a pinch of black pepper. You should not need to add any additional salt as the tuna and Tamari should provide enough. Beat the eggs together until smooth.
Create a well in the center of the tuna rice mixture. Pour the beaten egg into the well in the center. Allow the egg to settle for a moment and start cooking. Mix everything together well with a wooden spoon, scrambling the egg into the rice. Cook the egg through.
Thinly slice the avocado and roughly chop the cilantro. Transfer the egg fried rice to a serving plate or dish. Top with the remaining sliced scallion, avocado and cilantro. Serve immediately.