Clean the jar and lid with warm soapy water. Ensure the jar does not have any chips or bubbles in the glass.
Warm jar in a pot of hot water.
Rinse radishes under cool water.
Using a knife and cutting board remove the stem and root ends of the radishes.
Using a mandoline cut the radishes into 1/8 inch slices. Rinse the slices under cool water and drain.
Bring the vinegar, sugar, water, pickling salt, mustard seeds, black pepper, bay leaf, and crushed red pepper (if using) to a boil in a small stainless steel pot. Stirring until the sugar and salt have dissolved.
Place the radish slices in the hot jar.
Ladle the hot pickling liquid over the radishes, leaving 1/2-inch headspace.
Using a de-bubbler remove air bubbles.
Add more pickling liquid as needed to maintain 1/2-inch headspace.
Wipe the jar rim. Center the lid on the jar. Apply the ring, and adjust to fingertip-tight.
Cool on a wire rack for about 1 hour.
Place in refrigerator and chill for at least 6 hours before serving.
Store in the refrigerator for up to 3 months.
Notes
This easy sweet radish refrigerator pickle recipe comes from the Ball Canning Back to Basics Book on page 184.