Put rice syrup and ginger slices into a small saucepan. Heat over a low temperature until bubbling. Let it bubble for a minute or two, then turn off the heat.
Discard the ginger slices (or eat them!) and pour syrup evenly into the base of two ramekins. Set aside.
For the panna cotta:
Put coconut cream, brown rice syrup, vanilla, both gingers and the agar agar into a small saucepan and stir to combine. If there are any clumps of dried ginger, press them against the side of the saucepan to break them up.
Heat over a low-medium temperature until mixture is simmering. Simmer for five minutes, then turn off the heat (this step is essential to activate the agar agar).
Let the mixture cool for about 10 minutes, then strain through a fine sieve and pour evenly into ramekins. Refrigerate for a few hours until set and ready to serve. Unlike gelatin, agar agar will set at room temperature so you could leave them on the countertop if you prefer.
When it's time to serve, sit the ramekins in a larger bowl and pour boiling water around them (careful not to pour it onto the panna cotta itself). Let sit for a few minutes to melt the syrup.
Lift the panna cotta out, put a small plate or bowl on top then quickly and confidently flip them both over at the same time. Give it a single downwards shake if you like, to be sure the panna cotta has released, then remove the ramekins.
Dress with sliced fruit and serve immediately.
This recipe can easily be doubled or triped to serve more people.