To pickle asparagus, trim the spears, wash them, and combine them with onions, vinegar and spices in an air-tight container. For a spicier variation, add whole hot chile peppers.
Before pickling asparagus, sterilize the jars and lids by simmering them in water for five minutes. Let them cool to room temperature before proceeding.
Trim the woody ends of fresh asparagus, and cut them to a length that fits in your canning jar. In a colander, was the spears well, and allow them to drain. Trim 1/4 cup of pearl onions, and place them in the jar. Add the asparagus, 1/4 cup white wine vinegar, 1/4 cup cider vinegar and 1 cup of water.
Season with 1 sprig of fresh dill, 2 whole cloves, 3 cloves of garlic, 8 whole black peppercorns and 6 whole coriander seeds. Add 1/4 teaspoon red pepper flakes for heat. Place the lid on the jar, and refrigerate for up to four weeks.
For a sweet and spicy take on pickled asparagus, add 4 to 6 whole hot chile peppers and 4 tablespoons of sugar. For best results, use asparagus you have grown yourself or the freshest spears from the farmer's market. Thick spears work best because they do not get mushy in the jar. Wait at least a week before tasting for best flavor.