Chop the cauliflower into florets and halve the brussel sprouts.
Preheat oven to 400 F (204 C)
Mix batter ingredients together in a big bowl.
Add all the veggies to the bowl and mix well (you may want to use your hands) so that every piece is coated.
Place parchment paper down on 2 baking sheets. Evenly divide the veggies between the two sheets, ensure each piece has a bit of space around it to properly cook. Bake for 35 minutes, flip halfway.
Take the veggies out of the oven and pour the sweet Thai chili sauce over both baking sheets. Then mix really, really, really well so that every piece is fully coated.
Place back in the oven and bake for an additional 10 minutes.
Top with sesame seeds.