If you are grilling the asparagus: Begin by preheating the grill. While it heats, trim the asparagus. Hold each stalk by the end and bend the stalk. The thick white end will snap off about one-third of the way from the end. Discard it. Brush the tips with olive oil and place them up on the grill across the bars. Grill for 2 minutes and turn with long kitchen tongs. Grill for another 2 minutes and remove.

If you want to parboil the asparagus: Snap the thick stem ends off the asparagus as directed above. In a large skillet, bring about 1 inch of water to boil. Add 1 teaspoon of salt-this will maintain the asparagus's bright green. Add the asparagus, cook for 3 minutes, or until tender, and drain.

Peel, then cut the onions in half lengthwise. Place each half, cut side down, on a cutting board and thinly slice.

In a medium skillet, sauté the onions in the olive oil over medium heat, stirring, until translucent.

Preheat the oven to 350 degrees Fahrenheit.

Toast the bread lightly on a baking sheet for about 5 minutes. It should be firm, but not dry. Cut each slice in half.

To assemble the panini, arrange the 12 pieces of bread in front of you on the counter. Top each one with 2 asparagus spears and 1 tablespoon of sautéed onions. Season with a few twists of your pepper mill.