Bring a pot of salted water to a boil. Add the green beans and blanch for 1 minute, then immediately transfer to an ice bath to stop cooking. Drain and dry completely. (If you prefer very crisp beans, you can skip blanching and proceed directly to breading.)

Set up breading station

Place 1 cup all-purpose flour mixed with 1 tbs cornstarch, 1/2 tsp kosher salt, 1/2 tsp black pepper, and 1/2 tsp garlic powder in a shallow bowl. In a second bowl, whisk 2 large eggs with 1 tbs whole milk. In a third shallow bowl, combine 2 cups panko breadcrumbs, 1 tbs finely grated Parmesan (optional), 1/2 tsp kosher salt, 1/2 tsp black pepper and 1/2 tsp garlic powder.

Bread the green beans

Working in batches to avoid overcrowding, toss a handful of green beans in the seasoned flour to coat, shake off excess, dip into the egg wash, then press into the panko mixture until evenly coated. Place breaded beans on a baking sheet in a single layer. Repeat until all beans are coated.

Heat oil

Pour about 1 cup vegetable oil into a large skillet (enough to come about 1/3 inch up the side) and heat over medium-high until the oil registers 350°F (175°C) or a breadcrumb dropped in sizzles immediately and browns in ~30 seconds.

Fry the beans

Fry breaded green beans in batches (do not overcrowd) for 1.5–2.5 minutes per side, turning once, until golden brown and crisp. Use a slotted spoon or tongs to transfer fried beans to a wire rack set over a baking sheet or to paper towels to drain. Immediately season lightly with a pinch of salt while hot.

Keep warm

If frying multiple batches, keep finished batches in a 200°F (95°C) oven on a wire rack to stay crisp while you finish the rest.

Finish

Serve the crispy green beans hot with lemon wedges alongside the aioli for dipping.

For the Chinese mustard aioli

Make the aioli: In a small bowl, combine 1 cup mayonnaise, 2 tsp prepared Chinese hot mustard, 1 tsp rice vinegar, 1 tsp honey, 1 tsp sesame oil, 1 tsp soy sauce, and 1 tsp freshly grated ginger (if using). Whisk until smooth. Taste and adjust heat/sweetness: add a pinch more mustard for heat or an additional 1/2 tsp honey to mellow.

Adjust consistency and seasoning: If the aioli is too thick, whisk in up to 1 tsp water, 1/2 tsp at a time, until the desired consistency for dipping is reached. Season with 1/4 tsp salt or to taste.

Chill briefly: For best flavor, refrigerate the aioli for at least 10–15 minutes to let flavors meld. Bring to room temperature for a few minutes before serving if chilled for longer.