Combine the Olive oil, Lime juice, Schwartz Ground coriander, Sesame seeds and Crushed Chillies to make the dressing and leave to infuse for 1 hour.
Sear the tuna for 2 minutes on both sides. Sprinkle the Schwartz Blackened Cajun Seasoning on both sides and continue cooking for 2-3 minutes.
Mix together the red pepper, and spring onions in a bowl and drizzle with half of the dressing. Arrange on a plate, then place the seared tuna on the pepper mix and drizzle with the remaining dressing.