Steam the green beans for 2 minutes, then add the cauliflower and broccoli.
Steam for another 4 to 6 minutes or just until the vegetables are crisp-tender.
Do not overcook.
Rinse the vegetables under cold water until they are cool.
While the vegetables cook, begin making the marinade.
Place the sesame seeds in a small skillet over low heat and toast lightly.
Add the garlic and oil and cook, stirring, over very low heat for about 2 minutes.
Do not allow the garlic to brown at all or the taste will be bitter.
Remove from the heat and stir in the vinegar, honey, and tamari.
Place the cooked vegetables in a shallow serving dish.
Spoon the marinade over the vegetables.
Cover tightly and refrigerate for 4 to 6 hours or overnight.