Barbecue sweet potatoes with garlic and herb dressing

Method

1. Put each sweet potato on a large piece of foil. Drizzle over olive oil and season well. Wrap tightly and put in the barbecue embers for 45-60 minutes. Alternatively, roast in an oven heated to 200°C/180°C fan/gas 6 for 1 hour 20 minutes.
2. Meanwhile, wrap the garlic cloves in a little foil, drizzle with olive oil, and leave in the embers for 15-20 minutes until soft (or cook in the oven, as above, for 20 minutes). Finely slice the red onion and put in a non-metallic bowl with most of the lemon juice and a pinch of salt.
3. When the garlic is cool enough to handle, squeeze the flesh from the skins into a large bowl and drizzle with a little more olive oil. Mix in the soured cream or yogurt gradually to distribute the garlic evenly.
4. When ready to serve, add the chopped herbs, lemon zest and the remaining lemon juice, season and taste. Remove the onions from the lemon juice, squeezing them dry.
5. Open the sweet potato parcels, squash the flesh open a bit, spoon over the garlic and herb dressing, scatter with the onions and extra mint leaves, then serve in the foil.