For the steak sandwich, heat a griddle pan until hot. Brush half of the olive oil over the steak and fry for 3-4 minutes on both sides (for medium), or until golden-brown all over and cooked to your liking. Remove from the pan and leave to rest on a warm plate.
Drizzle the remaining olive oil over the bread and toast on the griddle for 2-3 minutes on both sides, or until golden-brown and crisp.
For the salsa, mix together all of the salsa ingredients in a bowl.
To serve, slice the steak into thick strips and serve on top of the toasted bread with the salsa spooned over the top.