In a small bowl, whisk together the chicken broth, cornstarch, soy sauce, lemon juice, lemon zest, sugar, and ground black pepper until the cornstarch is fully dissolved and the mixture is smooth. This sauce base can be set aside while you prepare the other ingredients. Mince the garlic, grate the ginger, trim and cut the asparagus into 2-inch angled pieces, and remove the tails from the shrimp if not already done. Having everything prepped and ready will make the stir-fry cooking process seamless since it moves quickly.
Heat 1 tablespoon of olive oil in a large skillet or wok over medium-high heat until shimmering. Working quickly, season the shrimp with 1/2 teaspoon salt and 1/4 teaspoon of the ground black pepper, then add them to the hot pan in a single layer. Cook for about 1-2 minutes per side until they turn pink and opaque, being careful not to overcook them. Transfer the cooked shrimp to a clean plate and set aside. I prefer to sear the shrimp first while the pan is hottest, which gives them a nice color and ensures they won't become rubbery when reheated later.
Add the remaining 1 tablespoon of olive oil to the same skillet over medium-high heat. Add the cut asparagus and cook for 4-5 minutes, stirring occasionally, until the pieces are tender-crisp with a slight char on the edges. Season the asparagus with the remaining 1/4 teaspoon salt and 1/2 teaspoon lemon pepper, tossing gently to distribute the seasonings evenly. Transfer to a plate and set aside temporarily.
Reduce the heat to medium and add the minced garlic and grated ginger to the same pan. Cook for about 1 minute, stirring constantly, until fragrant—this blooming technique releases the essential oils and deepens their flavors without burning them. I like to watch carefully during this step because garlic can go from aromatic to bitter quickly on high heat.
Pour the lemon sauce from Step 1 into the pan with the garlic and ginger. Stir constantly and simmer for about 1-2 minutes until the sauce thickens slightly and coats the back of a spoon—the cornstarch will continue to thicken the sauce as it heats. Return the cooked asparagus from Step 3 to the pan and toss gently to coat. Add the sesame oil for a subtle nutty finish, then return the seared shrimp from Step 2 to the pan and cook for just 1 minute until everything is heated through and the shrimp are warmed. Transfer to a serving dish, top with fresh parsley and red chili flakes, and serve immediately over rice if desired.