In a small bowl, mix together fish sauce, lime juice and honey. Place tuna in a large, plastic, sealable bag then pour fish sauce mixture over the tuna. Shake to combine. Refrigerate for 1 hour.
Heat 2 tablespoons olive oil in a wok over high heat. When the oil is very hot, almost smoking, place 1/2 tuna in pan; cook and stir for 1 minute, or until done to your preference. Transfer cooked fish to a large bowl. Repeat with remaining oil and tuna.
Toss warm fish with tomatoes, spring onion, red chilli, coriander and basil. Serve.