Cut the chicken breasts into 1/2-inch strips and season with salt and pepper. Heat 1 teaspoon of olive oil in a large skillet over medium-high heat. Cook half the chicken for 3-4 minutes until golden brown and no longer pink. Set aside and repeat with the remaining chicken.

In the same skillet, add 2 teaspoons of olive oil. Once hot, add sliced mushrooms and chopped onions, sautéing for 2-3 minutes until softened. Add minced garlic and cook for an additional minute.

Add the remaining teaspoon of oil and fresh asparagus. Sauté for 2-3 minutes until crisp-tender and vibrant green.

Return the cooked chicken to the skillet. Pour in sherry or chicken stock, scraping the bottom to deglaze. Bring to a boil for 1-2 minutes until liquid reduces to about 2 tablespoons.

Off the heat, stir in cold butter until melted and combined, creating a silky sauce. Serve immediately.