Rainbow Sourdough Milk Bread

Ingredients

• 3 tablespoons bread flour
• ½ cup whole milk
• 3 cups bread flour, plus more for dusting
• ¼ cup granulated sugar
• 1½ teaspoons fine sea salt
• ½ cup active sourdough starter (100% hydration, fed and bubbly)
• ½ cup warm whole milk (95°F / 35°C)
• 1 large egg, room temperature
• 4 tablespoons unsalted butter, softened and cubed
• 1 teaspoon beet powder (pink/red)
• 1 teaspoon turmeric powder (golden yellow)
• 1 teaspoon spirulina powder (green)
• 1 teaspoon butterfly pea flower powder (violet/blue)
• 1 large egg
• 1 tablespoon whole milk