Stove Top Brussels Sprouts

This is adapted from Jennifer Segal's recipe in Once Upon A Chef Cookbook -
  Butter-Braised Brussels Sprouts with Shallots

I was trying to use up scallions, red peppers and celery from my fridge, so I threw those in as well, and they took up the dressing well.  I needed to add more salt, pepper and vinegar, but that may well be because of the extra ingredients.  Here's the original:

Ingredients: 
3 Tbsp unsalted butter, divided
1 cup thinly sliced shallots
1 lb Brussels sprouts, trimmed but left whole
3/4 cup low-sodium chicken broth (I always use vegetable broth)
3/4 tsp salt
1/4 tsp freshly ground black pepper
1 tsp sugar
1 tsp white wine vinegar (or white balsamic)

extras -
2 stalks of celery, cut down the middle then sliced
1 small red pepper, but into chunks

Directions:
1) In a large skillet, melt 2 Tbsp of the butter over medium heat.  Add the shallots and sprouts and cook, stirring frequently, until the shallots are starting to brown and the sprouts are bright green, about 5 minutes.

2) Stir in the broth, salt, pepper and sugar; cover with a lid and lower the heat to medium-low.  Simmer for 5 minutes, then remove the lid and continue simmering for 7-10 minutes more, stirring occasionally until the sprouts are tender and the liquid is reduced to about 1/4 cup.

3) Stir in the remaining 1 Tbsp butter and the vinegar.  Taste an adjust the seasoning if necessary.

These can be prepared up to 2 days ahead, then reheated gently in the microwave or stovetop.