Place the lukewarm water, yeast and sugar together into a bowl. Give it a stir and set aside for a few minutes.
In a stand mixer bowl fitted with a dough hook attachment, add in the flour, milk, oil, and sea salt. When the yeast has activated and is bubbly, add it into the flour mixture and knead until the dough becomes smooth and shiny. Add in the Suncore Activated Charcoal Coconut Supercolor Powder and keep kneading until the black colour is incorporated into the dough.
Transfer the dough to a lightly greased bowl and cover with plastic wrap. Let it sit in a warm place to double in bulk.
Line a large baking sheet (12" by 17") with parchment paper.
When the dough has doubled in size, punch down the dough and divide into 8 equal pieces (I use a scale to do this).
Form each piece into a ball and roll into a rectangle about 4.5" in length for hotdog buns. Press down the tops to flatten so they don't get too poofy. For hamburgers, form each ball into a 3.5" diameter and press down to flatten.
Place onto the lined baking sheet. Repeat with the remaining dough.
Cover the buns with a piece of loose plastic wrap and let it rise for another 30-40 minutes, until slightly puffy.
Preheat oven to 400°F.
Remove the plastic wrap and lightly brush the tops of each bun with the beaten egg. Sprinkle with sesame seeds if desired.
Bake the buns for 20-22 minutes, or until the internal temperature of the bread reaches 190F.
Remove and let cool on a rack before slicing.