Preheat the oven to 360F/180C. Open the vanilla pod with a knife, scrape out the vanilla seeds and combine them with the sugar. Place the rhubarb in a deep oven-safe dish with the vanilla sugar and mix until the sugar covers all the rhubarb pieces evenly. Place the rhubarb into the oven and roast for 20 minutes. Once done, allow it to cool while you finish making the pancakes.
While the rhubarb is roasting in the oven, combine the dry pancake ingredients (flour, oats, sugar, salt, ground flax seeds) in a large bowl. In a smaller bowl, combine the wet pancake ingredients (mylk, oil, vinegar). Then pour the wet ingredients into the bowl with the dry ingredients and combine, ensuring the batter is free of lumps without overmixing!
Heat a small pancake pan over medium heat, add some oil to the pan when it’s hot. Then pour about 1/4 of a cup of the pancake batter into the pan. When bubbles form on top of the pancake, and the bottom side looks golden brown, carefully flip the pancake over and brown the other side. Repeat until all the batter has been used.
Once the pancakes are done, serve immediately and top with the roasted rhubarb and some maple syrup, yoghurt, and granola if you wish.