To make the mint and vanilla syrup, in a saucepan, add the water and sugar and let boil until sugar is completely dissolved. Remove from the heat.
Slice the vanilla bean lengthwise and carefully with a knife, scrape out the seeds. Add the seeds, the bean and mint leaves to the syrup. Let steep for at least a half hour.
To serve:
Preheat the grill to medium high.
Brush the pineapple slices with a little canola oil and place on the grill for 3 to 4 minutes per side, until the pineapple has grill marks and the juices start to caramelize.
Lay the grilled pineapple in a baking dish and pour the syrup over it, making sure to cover all of the slices. You can make this ahead and keep in the refrigerator.
To serve, place a slice of pineapple on a plate, add a generous scoop of vanilla ice cream on top. Drizzle on some more of the syrup on top and garnish with a couple of mint leaves.