Mini Beef Wellington Bites Recipe

Name: Mini Beef Wellington Bites Recipe
Ingredients: ½ pound filet mignon (or about 2 small filets); ½ + ¼ teaspoon salt, divided; ½ + ¼ teaspoon pepper, divided; 2 tablespoons grapeseed oil; 2 tablespoons butter; 6 ounces baby bella mushrooms, very finely chopped; ¼ cup finely chopped shallot; 3 cloves garlic, minced; 1 tablespoon finely chopped curly parsley, plus 12 small sprigs for serving; 1 teaspoon dried thyme; 1 teaspoon dried rosemary; 1 puff pastry sheet, thawed; 1 egg; 1 teaspoon water; 1 tablespoon mayonnaise; 1 tablespoon Dijon mustard