Cut capsicums into quarters and place with the outside facing upwards on a baking tray. Brush with very little olive oil and place under the grill until the skin starts to blister and some spots start to darken. Allow capsicums to cool then remove the skin.
In the meantime toast the cumin in a small frying pan over medium heat until aromatic. Allow to cool and crush in a mortar or coarsely grind in a spice mill.
Dice the entire lemon very finely. Cut the capsicums into bite-sized pieces and mix with lemon and cumin. Add some olive oil and salt to taste then chill until serving.