Peel and slice the yellow onion into 1/2-inch thick rings, separating them carefully.
In a shallow bowl, whisk together the chickpea flour, smoked paprika, 0.5 tsp of the garlic powder, 0.25 tsp of the sea salt, and the black pepper.
Slowly pour the light beer into the flour mixture, whisking until a thick, smooth batter forms.
Place the liquid egg whites in a separate shallow bowl and whisk until slightly frothy.
Dip each onion ring into the egg whites, then dredge thoroughly through the beer batter until fully coated.
Arrange the rings in a single layer in an air fryer basket and lightly mist with avocado oil.
Air fry at 375°F for 10-12 minutes, flipping halfway through, until the coating is crisp and golden brown.
While the rings cook, stir together the Greek yogurt, Dijon mustard, lemon juice, and the remaining garlic powder and sea salt to create a zesty dipping sauce.