1. Halve or quarter the beetroot, depending on the size.
2. Heat the olive oil in a large non-stick pan.
3. Add the beetroot and sauté for 2-3 minutes, tossing well to coat.
4. Add the balsamic vinegar, season and cook 1-2 minutes longer, until reduced right down to a syrupy glaze.
5. Transfer to a serving bowl to cool; cover and chill.
6. Can be done up to 1 day ahead.
7. Remove from fridge 30 minutes before serving.
8. Crumble over the Roquefort.
9. Sprinkle with the sesame seeds.