First, give your fresh green beans a good wash and trim off the stem ends. You can leave them long or snap/cut them into smaller pieces if you prefer – I usually leave them whole for that classic look.
Next, let's make that flavorful batter. In a medium bowl, whisk together the flour, onion powder, garlic powder, salt, black pepper, cayenne pepper, and cumin. Set this aside.
Now, prepare the dipping sauce. In a small bowl, simply mix together the mayonnaise and sriracha until smooth and well combined. Taste it and add a little more sriracha if you like things hotter, or a tiny squeeze of lime juice if you want some brightness. Cover and pop this in the fridge while you fry.
Time to get the oil ready! Pour the vegetable oil into a heavy-bottomed pot or deep skillet. You want about 1-2 inches of oil. Heat the oil over medium-high heat until it reaches about 350°F (175°C). If you don't have a thermometer, you can test it by dropping a tiny pinch of flour in – it should sizzle immediately.
Now for the coating! You can either moisten the beans slightly by tossing them with a tablespoon or two of water or milk right before adding them to the flour mixture, or you can use a classic wet-dry method. For simplicity today, let's go with the slightly damp bean method. Add the trimmed, slightly damp green beans to the bowl with the flour mixture and toss them really well until they are evenly coated. You might need to do this in batches.
Carefully add the coated green beans to the hot oil, working in batches so you don't overcrowd the pan. Overcrowding lowers the oil temperature and makes the beans greasy instead of crispy. Fry for 3-5 minutes, flipping them occasionally, until they are golden brown and crispy. They cook fast!
Use a slotted spoon or spider to remove the fried green beans from the oil and transfer them to a wire rack set over a baking sheet lined with paper towels. This lets the excess oil drain off and helps keep them crispy. Sprinkle them with a little extra salt while they're hot, if you like.
Repeat with the remaining green beans until they are all fried.
Serve them immediately with that delicious sriracha mayo for dipping. Get ready for applause!