Peel the onion and garlic and finely chop. Chop cilantro, half jalapeños, remove seeds, and finally chop. Wash cucumber, halve, and finely dice. For the guacamole, halve avocado and remove pit and flesh. Transfer half of the flesh to the bowl and mash. Mix with lime juice and orange juice until creamy. And onion, cilantro and jalapeños and mix to combine. Season with garlic, cumin and salt to taste.

Dice remaining avocado and fold into guacamole with cucumber.

Season the tuna fillets with salt and pepper, rub with oil and fry in a non stick pan set over high heat. Fry for approx 30-60 seconds on each side for a rare seared steak. Serve immediately with a side of the guacamole, a sprinkle of lemon juice and a drizzle of olive oil. Enjoy!