1.Heat oil in small frying pan; cook onion over low heat, stirring occasionally, about 10 minutes or until soft. Add sugar and vinegar; cook, stirring, about 5 minutes or until caramelised. Remove from pan.
2.Meanwhile, cook seasoned steaks in heated oiled large frying pan until cooked as desired.
3.To make beetroot salsa, combine ingredients in medium bowl; season.
4.To make aioli, combine mayonnaise and garlic in small bowl; season with salt and pepper.
5.Sandwich rocket, tomato, steaks, onion, salsa and aïoli between toast slices.