Preheat oil in a deep fryer or heavy-bottomed pan to 180°C (350°F). Use enough oil to fully submerge the jalapeño rings.
In a mixing bowl, whisk together the self-raising flour, cornflour, and baking powder until well combined. Slowly pour in the chilled pale ale, whisking until the mixture becomes smooth and lump-free.
In a separate small bowl, mix the additional cornflour with salt and pepper.
Lightly toss the jalapeño slices in the seasoned cornflour, ensuring each ring is evenly coated. Then dip them into the beer batter, coating completely.
Using a slotted spoon or tongs, lift the battered jalapeños and let the excess drip off. Gently lower them into the hot oil and fry for 1–2 minutes until puffed and golden brown. Fry in batches to avoid crowding the oil.
Transfer fried jalapeños to a paper towel-lined plate to drain excess oil. Serve hot.
