For the brioche buns:
- In a small bowl, dissolve the yeast into the water and the lukewarm milk.
- Place all the ingredients except for the salt into the bowl of a stand mixer. Mix on speed 1 for about two minutes. Add the salt. Mix on speed 4 for two minutes. Switch to speed 6 and mix until the dough becomes smooth and slaps the bowl.
- Remove from the bowl and shape into a ball with your hands. Place into the bowl again and let rise until doubled in size, about 2 hours.
- Shape the dough: divide the dough into 6 equal parts. Use your hands to flatten each dough portion. Fold the tips into the centre, and repeat again from all sides, until you get a little pouch. Flip it over, trap the dough with your hands, press a little bit and roll it onto the worktop. It must stick to the worktop a little bit. Place each little ball onto a baking tray lined with parchment paper. Cover with a cloth and let rise until the dough is strong and you feel the air inside, about one hour minimum.
- Brush with beaten egg, sprinkle some black sesame seeds and pumpkin seeds on top, and bake at 190° C for about 15 minutes or until golden-brown. Transfer to a cooling rack and set aside.
For the beetroot patties:
- Preheat the oven at 180° C and line a baking sheet with parchment paper or foil. Set aside.
- Boil the quinoa according to the package instructions. Set aside.
- Place the beetroot onto the baking sheet, drizzle some olive oil and roast for about 30 minutes. Remove from the oven and set aside to cool.
- Place the roasted beetroots in a food processor and pulse 2 or 3 times – you need some texture for the burgers, so make sure you don’t mash them completely.
- Transfer the beetrootss into a large bowl, add all the other ingredients and stir to combine. If the texture is too mushy add more rolled oats or breadcrumbs until you obtain the desired consistency.
- Using a measuring cup or your hands, shape the burgers and place them on a lined baking sheet.
- Bake in the oven for 15 minutes on one side, then flip over and bake for 15 more minutes.
For assembling the burgers:
- Mash the avocados with a fork, and season with lemon juice, salt, pepper and chilli flakes.
- When burger buns are baked, cut in halves, add the beetroot patties, and generously spread the avocado dip on top (and/or underneath). Sprinkle some basil leaves and serve immediately.