salt and black pepper
Add the fennel, onion, brown sugar, vinegar, fennel seeds, salt and black pepper to taste in a dutch oven.
Toss everything until well combined, cover and bring to a boil over medium-high heat.
Reduce the heat to medium low or low, continue cooking until fennel and onions are soft and the texture becomes thick and jam like, 30 to 40 minutes.
Remove from the heat, and let cool.
Serve or place into a jar, seal well, put in the refrigerator, and it can last for a few weeks.