Mix sesame paste, rice vinegar, soy sauce, sugar, chili oil and sesame oil in a bowl or blender and chill. (Can be made 2 days in advance).
Cut off broccoli heads and break them into florets. Peel stalks if necessary and slice them into 1/4 inch slices. Cut cauliflower into small florets about 1 1/2 inches wide. Blanch the vegetables in a large saucepan of boiling salted water for 4 minutes. Plunge into cold water then drain. Dry in a salad spinner or colander. Arrange on a platter pour dressing over top and serve.