For the salad: Boil eggs for about 10 minutes until they are hard-boiled. Rinse with cold water and set aside until cool enough to handle. Peel hard-boiled eggs and chill.
Fry bacon and drain on paper towels.
For the vinaigrette: Through the feed opening of a running blender add, 1 at a time, the vinegar, pomegranate seeds, honey, salt and pepper. Leaving the blender running, add the olive oil in a slow, thin stream. Strain through a fine mesh strainer and set aside until needed.
For the tempura and sandwiches: Heat oil in a deep-fryer to 375 degrees F, or as directed in manufacturer's instructions for similar foods.
In a mixing bowl large enough to accommodate the stuffed sandwiches, combine flour, cornstarch, and baking powder. Add seltzer water in a stream while whisking constantly. Dip the stuffed sandwiches in the batter to coat. Add, 1 at a time, to the deep-fryer basket which has been immersed in the hot oil. Fry until golden brown and drain on paper towels.
Chop eggs and gently toss with spinach, crumbled bacon, and avocado with enough of the dressing to coat.
Arrange salad on plates with tempura fried stuffed sandwiches.