Granny's Homemade Sourdough Pretzels

Ingredients

• 1 1/4 cups (300 ml) warm water
• 1 cup (224 grams) active sourdough starter
• 1 1/2 teaspoon salt
• 1 tablespoon granulated sugar
• 3 1/2 cups (490 grams) unbleached all-purpose flour
• 2 quarts (2 liters) water
• 1/3 cup (70 grams) baking soda
• 1 egg white, lightly whisked
• Coarse salt to garnish