Peel ginger and finely chop. You should have about 1/4 cup (50 mL). Slice jalapeños in half lengthwise, discard seeds and finely chop. Pour undiluted broth into a large wok or wide saucepan. Add ginger, jalapeños and garlic. Bring to a boil over high heat. Gently boil until liquid is reduced by two-thirds, from 6 to 8 minutes. Remove from heat and stir in butter. Set aside. If making ahead, pour into a jar and refrigerate up to 2 days.
Bring a large pot of salted water to a boil. Fill a large bowl with ice water. Cut large baby carrots in half, leaving smaller ones whole. Cut broccoli into bite-size florets. You should have about 4 cups (1 L) broccoli. Once water is boiling, add carrots and partially cook just until slightly crunchy, from 5 to 6 minutes. Remove and immediately plunge into ice water. Add broccoli and partially cook just until tender and bright green, from 1 to 2 minutes. Immediately plunge into ice water. When vegetables have cooled completely, remove from water and pat dry with paper towels.
Core and seed peppers, then cut into bite-size strips. Cut each strip in half horizontally. Remove stems and strings from snow peas. All vegetables can be prepared up to this point and refrigerated up to 1 day. Place carrots and broccoli in one bag; peppers and snow peas in separate bags.
Before serving, place wok or wide saucepan containing broth mixture over high heat. When liquid starts to bubble, add peppers and cook, stirring often, for 2 minutes. Add snow peas and stir for 30 seconds. Add remaining vegetables and stir until heated through, from 2 to 3 more minutes.