Found it: In Everyday with Rachael Ray
This is an interesting new way to serve asparagus, and I'm always interested in new ways to serve vegetables. It's a little plain, but you could probably fix that by adding more spices to the batter or adding spices to the finished product. I haven't tried it yet, but I'm guessing you could also replace the seltzer water in the batter with beer for beer battering.
1 lb asparagus
4 cups vegetable oil (just use enough to get about an inch/two inches in the bottom of the kettle you're using, or use a deep fryer if you have one)
3/4 cup flour
1/2 cup corn starch
3/4 tsp salt
1/2 tsp baking soda
1/2 cup seltzer water, room temperature
For dipping sauce:
1/4 cup plain yogurt
2 tbsp mayonnaise
2 tbsp dijon mustard
1 tbsp honey
Heat the oil in a large saucepan for several minutes on high, then turn it down to medium-high to maintain temperature of about 375 degrees. Combine all batter ingredients to form a sticky batter. Dip asparagus into batter one at a time and place in the oil. Cook the asparagus in 3-4 batches, each of which will take around 2 minutes. You can keep earlier batches warm in a 200 degree oven if needed. They're done when they're golden brown. Serve hot.
Combine the four sauce ingredients to make a dipping sauce.