Cut squid tubes into rings. Blanch in boiling water to cover 30 seconds or until opaque. (Water doesn't have to return to a rolling boil.) Don't overcook or squid will become tough. Plunge in ice water to chill. Drain.
Combine squid, mangoes, and lime juice in a small bowl.
Whisk together mustard, vinegar, and olive oil. Stir in cilantro and next 3 ingredients. Fold in squid mixture.
Cover and chill until ready to serve. Top baguette slices with salad, using a slotted spoon.