Flatiron Steak Sandwich with Cucumber-Ginger Salad and Black Chile Mayonnaise

Ingredients

• 2 chipotle chiles
• 1 ancho chile
• 1 cup grapeseed oil
• 1 large egg yolk, preferably from a pasture-raised egg
• ¹⁄₂ tsp. minced garlic
• Juice from 1 lime
• ¹⁄₄ tsp. sugar
• ¹⁄₂ tsp. kosher salt
• 1 (1-lb.) flatiron or sirloin steak
• Kosher salt and freshly ground black pepper
• 1 tsp. vegetable oil
• 2 cups peeled, cored, and julienned English cucumber
• 2 Tbsp. peeled and julienned fresh ginger
• 1 cup cilantro leaves
• 4 Tbsp. Black Chile Mayonnaise
• 4 ciabatta rolls
• Juice of 1 lime