Preheat your air fryer to 200°C (400°F) so it's ready to go.
Trim the ends off your fresh green beans and give them a quick rinse under cold water. Pat them completely dry with a kitchen towel — this helps them crisp up during roasting.
In a mixing bowl, toss the green beans with a tablespoon of neutral oil, making sure each bean is lightly coated. This helps with browning and crispness.
Sprinkle the beans with a pinch of salt and half a teaspoon of garlic powder if you like. Toss again to evenly distribute the seasonings.
Arrange the beans in the air fryer basket in a single layer, spreading them out as much as possible to ensure even cooking. Overcrowding will cause uneven crisping.
Cook the green beans for 8 to 10 minutes, shaking the basket halfway through to promote even browning. You'll hear a gentle sizzling and see blistered, golden edges forming.
Check the beans — they should be crispy around the edges and tender inside. If needed, cook for an additional 2 minutes, but keep a close eye to prevent burning.
Once done, transfer the beans to a serving plate. Squeeze fresh lemon juice over them for brightness and finish with flaky sea salt to taste.
Serve immediately to enjoy their full crispy texture and smoky flavor — perfect as a snack or a side dish.