Chill four glass dishes in the fridge and preheat the oven to 100°C.
Shave 6 long ribbons from one rhubarb stalk and chop the rest into 1cm pieces.
Simmer 100ml water, sugar, and grenadine, then soak rhubarb ribbons for 10 minutes.
Dry the ribbons on a silicone mat in the oven for 25 minutes, then increase oven heat to 140°C.
Macerate 450g rhubarb with sugar and 100ml syrup for 30 minutes, then bake covered for 25 minutes.
Cool the baked rhubarb in its juice, then strain and reserve 200ml of liquid.
Infuse ginger and softened gelatine in 200ml juice over low heat until dissolved.
Layer 40g chopped rhubarb and 50g larger pieces in glasses, add 4 tsp jelly, and chill for 15 minutes.
Boil cream, milk, sugar, and vanilla, then pour over whisked egg yolks.
Heat custard to 75°C, then blend in gelatine over ice-cold water until cool and airy.
Top the jelly with custard and refrigerate for 3 hours or overnight.
Boil water, honey, glucose, and sugar until it becomes a light golden caramel.
Stir in bicarbonate of soda, pour onto a silicone mat, and allow to cool before breaking.
Garnish with honeycomb, reserved jelly dots, rhubarb crisps, and sliced angelica.