Fritto misto, which means "fried mix," is a classic Italian antipasto.
To separate artichoke bottoms, slice off upper two-thirds of each bulb, and discard. Snap off tough outer leaves; scoop out bristly choke with a spoon. Using a vegetable peeler or paring knife, remove green skin from around white center. Thinly slice bottoms.
In a medium bowl, stir together the artichoke bottoms, fennel, lemons, and buttermilk to coat evenly. Place flour in a separate bowl, and season with salt and pepper; whisk to combine.
Pour the oil into a heavy, deep-sided skillet or deep fryer; place over medium-high heat until it registers 370 degrees on a deep-fry thermometer. Drain vegetables and lemons, discarding liquid.
Working with one piece at a time, dredge vegetables and lemon in flour, and carefully place in the hot oil. Cook 6 to 7 pieces at a time until golden brown, about 3 minutes.
Using kitchen tongs or a slotted spoon, transfer vegetables and lemons to drain on a paper-towel-lined plate. As soon as each batch is done, sprinkle with salt, and serve immediately.