COMBINE vegetable broth with water in a large saucepan. Boil, then add roasted cauliflower (from Cauliflower Tacos) and cook until warm, 2 to 3 min. Scrape into a blender and whirl until smooth. Return to pan and set over medium-high. Stir in cream and lime juice until warmed through.
BRUSH tortillas with canola oil. Slice each into quarters, then cut into 1/2-in. strips. Arrange on an unlined baking sheet. Bake in centre of oven until golden, 5 min.
WHISK 1/4 cup yogurt with mayo, Dijon and salt in a large bowl until combined. Add lettuce and coleslaw. Toss to coat.
DIVIDE soup among 4 bowls. Top with remaining 1/4 cup yogurt, then pepitas and toasted tortillas. Serve with salad.