Place juice and sugar in a pan and bring to the boil. Simmer rapidly over high heat until liquid has reduced by half. Set aside.
Place gelatine leaves in a bowl and cover with cold water. Set aside.
Place cardamon seeds in a saucepan over medium heat and dry-roast for 1 minute to release their aroma. Add cream, vanilla pod and seeds, then bring to the boil. Add orange syrup, stir to combine and remove pan from heat.
Squeeze excess water from gelatine and add to orange mixture. Stir until gelatine dissolves. Strain mixture and divide among eight 120ml moulds (the mixture won't completely fi ll the moulds).
Refrigerate for 5-6 hours until set.
For the caramelised orange, preheat a grill to high. Place segments on a tray lined with baking paper and sprinkle both sides with sugar. Grill for 5 minutes or until sugar starts to caramelise. Cool.
For praline, line an 18cm x 27cm slice pan with baking paper and scatter evenly with nuts. Place sugar and 1 cup (250ml) of water in a pan over medium-high heat and stir to dissolve sugar. Bring syrup to a rapid simmer. When it turns to a golden toffee (20-30 minutes), quickly pour syrup into the slice pan, taking care as it will be very hot. Cool completely, then transfer to a board and roughly chop.
To serve, run a knife round edge of moulds and turn panna cotta out onto plates. Serve with orange and praline.
