1.Wash coriander well, paying particular attention to roots. Finely chop coriander roots and stems; reserve leaves to serve. Finely grate rind from 2 limes; you need 1 tablespoon rind. Juice 1 lime; you need 2 tablespoons juice.
2.Place coriander root and stem mix, lime rind and juice in a medium bowl with 1 tablespoon of the oil; mix well, then season.
3.Cut brussels sprouts in half lengthways. Par-cook sprouts in a saucepan of boiling water for 1 minute or until crisp-tender. Transfer sprouts to a large bowl of iced water for 1 minute; drain. Add sprouts to coriander marinade; toss to coat. Cover; refrigerate for 20 minutes.
4.Meanwhile, combine aioli and sriracha in a small bowl. Cover; refrigerate until ready to serve.
5.Preheat a chargrill plate (or barbecue) over medium-high heat. Thread sprouts onto 8 metal skewers; brush with remaining oil. Cook skewers, in two batches, for 4 minutes on each side or until char marks appear and sprouts are crisp-tender.
6.Serve skewers with sriracha aioli, reserved coriander leaves and remaining lime cut into wedges.