For the dipping sauce, place all the sauce ingredients in a bowl and whisk until combined. Taste and adjust seasonings, if necessary. Set aside.
To prepare the bloomin’ onion petals, in a large bowl, whisk together the milk and vinegar. Set aside.
Peel and cut off both ends of the onion. Cut the onion in half vertically (from where the stem was), then cut each half into thirds to make about 1-inch wedges. Separate the petals and place them in the bowl with the milk and vinegar. Press the onions down so they’re submerged and let them soak for 30 minutes.
In a large bowl, whisk together the flour, smoked paprika, onion powder, salt, black pepper, garlic powder, and cayenne pepper until combined.
Working in batches, use a slotted spoon to remove the onions from the liquid and transfer them to the flour mixture. Toss until they’re fully coated in the seasoned flour.
Place the coated onion petals back into the liquid and repeat the process so they’re double coated. Transfer them to a wire rack and set aside for at least 10 minutes. Doing this allows the breading to adhere to the onions before frying.
Meanwhile, heat the vegetable oil into a deep sauté́ pan or Dutch oven over medium high heat (the oil should be about 3 inches deep - add more if needed).
Once the oil is hot, fry the onion petals in batches until they’re golden and crispy, 5 to 8 minutes.
Remove the onion petals from the oil and transfer them to a wire rack or paper towel–lined plate to drain excess oil. Immediately sprinkle them with flakey salt while they’re still hot. Repeat with the remaining onions and serve immediately with the dipping sauce. ENJOY!