In a bowl or wide-mouth jar, whisk together 1 teaspoon cornstarch and 2 tablespoons soy sauce until smooth. Add 1 tablespoon rice vinegar, 1/4 cup hoisin sauce, 1-1/2 teaspoons Sriracha (plus more as desired), 2 tablespoons light brown sugar, 2 teaspoons ginger paste, and 2 teaspoons minced garlic. Whisk until fully combined and set the sauce aside.

Heat 1 tablespoon toasted sesame oil in a large nonstick skillet over medium-high heat until shimmering.

Add the white parts of the green onions, 1 large diced red pepper, and the remaining 3 teaspoons minced garlic to the skillet. Cook, stirring occasionally, until the pepper begins to soften, about 3 minutes.

Push the vegetables to the edges of the skillet. Increase the heat to high and add 1 pound lean ground beef (93/7) to the center. Season the beef with salt and pepper to taste. Let the beef brown undisturbed on one side for about 1 minute, flip and brown the other side about 1 minute, then break the beef into crumbles. Continue cooking, stirring occasionally, until the beef is fully browned and any liquid has evaporated, about 5–7 minutes.

Reduce the heat to low. Pour in the prepared sauce and add 1/3 cup roasted cashews. Cook, stirring occasionally, until the sauce thickens and coats the beef, about 2–4 minutes. If using basil, stir in half of the 1/2 cup torn basil now.

Taste and adjust seasoning with more Sriracha, salt, or pepper if desired.

Serve the beef warm over cooked white rice if using. Garnish with sesame seeds (optional), the green parts of the green onions, the remaining basil (if using), and optional Avocado-Cucumber Salad.