- Cut cabbage lengthwise into 4 to 6 wedges. Cut out core. Cut each wedge crosswise into very thin slices. You should have about 22 cups.
- In a large non-reactive bowl, combine cabbage, carrots and salt. Place a plate on top to weigh down vegetables. Cover and let stand at a cool room temperature for at least 12 hours or for up to 24 hrs.
- Prepare canner, jars and lids
- In a colander working in batches, drain vegetables and rinse well. Drain again, squeezing out as much liquid as possible. Spread out on towel-lined baking sheets to drain any remaining water.
- In a pot combine sugar, celery seeds, mustard seeds, pepper and vinegar. Bring to a boil over medium heat, stirring often until sugar is dissolved. Boil for 1 minutes. Reduce heat to low and keep liquid hot.
- Working with one jar at a time, pack vegetables into hot jars, leaving room for liquid and 1" headspace. Pour in hot pickling liquid, leaving 1/2" headspace. Remove air bubbles and adjust headspace as necessary. Wipe rim and place hot lid disc on jar. Screw band down until fingertip-tight.
- Place jars in canner and return to a boil. Process 500mL jars for 15 mins and 1L jars for 20 minutes. Turn off heat, remove canner lid and let jars stand in water for 5 minutes. Transfer jars to a towel-lined surface and let stand for 24 hours. Check lids and refrigerate any jars that are not sealed.
- When serving, open jar and drain coleslaw in a sieve. Transfer to serving dish. In a small bowl combine the sunflower oil and Dijon mustard and toss with coleslaw just prior to serving.