Polish Sweet-Sour Red Cabbage (Czerwona Kapusta Zasmażana)

1 (3-pound) head red cabbage (washed, dried, cored, and shredded)
1 medium onion (shredded)
2 tablespoons butter (or canola oil)
1 cup water
4 tablespoons red-wine vinegar
4 tablespoons brown sugar (firmly packed)
1/2 teaspoon black pepper
1 teaspoon salt

• In a large pot or Dutch oven, cook cabbage and onion in butter or oil on medium heat until it collapses, about 5 minutes.
• Meanwhile, in a small bowl, mix together water, vinegar, brown sugar, pepper, and salt until sugar is dissolved.
• Add to cabbage mixture, combining well.
• Bring to a boil, then reduce heat to medium-low and cover tightly.
• Continue to cook, stirring occasionally, until cabbage is tender but still a little al dente, about 15 minutes.
• Refrigerate overnight to improve flavor.

NOTES:

• I made this for Wigilia in 2018 and liked it's mild flavor
• MAKE IT AHEAD OF TIME.  S/B SERVED COLD.
• I didn't have red wine vinegar but used some Trader Joe's pomegranate vinegar instead
• The recipe says to shred the cabbage and onion, but clearly that's not what is pictured.  I chopped the cabbage into roughly 1/2" sized pieces.
• I did try to shred the onion, but what a mess!  Just chop it into reasonably small pieces.

SOURCE:

https://www.thespruceeats.com/polish-braised-red-cabbage-recipe-1137527

(Says it can be frozen for 6 months.)