I recently acquired a new cookbook and--foolishly or bravely--used three untried recipes from it to serve at the party. The book is Entertaining for a Vegetarian Planet by Didi Emmons. I have some quibbles with it, but if you have some common sense and trust your instincts, you can get inspiration from the recipes but alter them to suit your taste.
This dish should be made at least 24 hours before you serve it; I made it around 48 hours before the party. These will keep about two weeks in the fridge.
If you use radishes, don't be shocked when they turn pink through and through. The pickling solution will also affect the color of broccoli.
Here's her recipe for pickled veggies, slightly altered:
1 1/2 cups white vinegar
1 cup thinly sliced fresh ginger
4 to 6 tablespoons sugar, or to taste
2 teaspoons kosher salt
8 cups sliced vegetables (variously colored bell peppers, carrots, etc.); florets of broccoli or cauliflower; halved red radishes; whole or halved pearl onions
In a large saucepan, bring the vinegar, ginger, sugar, and salt to a boil. Remove from the heat and let stand for 15 minutes.
Place vegetables in a large, shallow bowl. Bring the vinegar mixture a boil again and pour it over the veggies. Toss well and transfer the vegetables to a container with a tight-fitting lid. Allow the mixture to cool before covering. Refrigerate overnight.
I served these in a black casserole dish that really showed off the colors of the vegetables. A glass bowl would also be lovely.