• 21 russet potato, scrubbed and dried
• 10½ tbsp olive oil
• 5¼ tsp kosher salt
• 2⅔ tsp black pepper
• 21 tbsp butter, for serving, optional
• 0.3 l sour cream, for serving, optional
• 10½ tbsp chives, chopped, for serving, optional

Metric measurements are approximate conversions.