From the Italian phrase bagno caldo (hot bath), bagna cauda is a warm sauce made with olive oil, anchovies, and garlic, and served with bread and raw vegetables, such as bell peppers and zucchini, for dipping. If you have a fondue pot handy, use it to keep this dip warm while guests help themselves.
Combine boiling water and sun-dried tomatoes in a bowl; let stand 30 minutes or until soft. Drain and mince; set aside.
Heat 1 teaspoon oil in a medium saucepan over medium heat. Add bell pepper, minced onion, and garlic; sauté 5 minutes or until tender. Add anchovies; cook 1 minute, stirring frequently. Add sun-dried tomatoes and capers; cook for 1 minute. Stir in broth, mustard, and salt. Bring to a boil; reduce heat, and simmer 2 minutes. Stir in remaining oil, and remove from heat. Add green onions and vinegar. Serve warm.