Steam-heat-only, food-preparation bowl structure and related methodology. The bowl structure includes (a) an outer bowl unit having a water well disposed adjacent its base, (b) an inner bowl unit nestable in the outer unit in a condition having its base spaced above the water well whereby water in the well does not contact the inner bowl's base, and with a generally closed, bowl-shaped void space then existing between the two units, the inner unit being constructed to receive a mixable mass of food, and (c) a controllable heater disposed within the well, operable to heat water contained therein to produce steam within the void space. The related methodology includes the steps of (a) applying mixing action to such a mass within the inner bowl unit, and while so applying, vapor-heating the mass indirectly and solely by an adjacent body of steam disposed in the void space between the units.