Curtis Stone's Steak Crostini with Arugula Pesto Recipe

Ingredients

• 1 red onion, thinly sliced (about 1 cup)
• 1/4 cup fresh lemon juice
• 1/4 cup distilled white vinegar
• 1 teaspoon kosher salt
• 1 cup fresh arugula, lightly packed
• 1/2 cup fresh basil leaves, tightly packed
• 1/3 cup pine nuts or almonds, toasted
• 1 lemon, peel finely grated
• 1 clove garlic
• 1/2 cup freshly grated Parmesan cheese
• 1/2 cup extra-virgin olive oil
• 1/2 loaf ciabatta bread
• 2 tablespoons olive oil
• 1 rib-eye steak, cooked to medium-rare doneness, chilled
• 1 cup fresh arugula