Tomato Fondue (Fondue de Tomates)

Heat large saucepan of water over high heat to boiling. Immerse tomatoes in boiling water for 10 seconds. Remove tomatoes with slotted spoon; rinse under cold running water to cool; drain. Core and peel tomatoes. Cut tomatoes crosswise in half; squeeze firmly into sieve over bowl to remove seeds. Discard seeds; reserve strained tomato liquid. Chop tomato pulp fine.

Melt 2 tablespoons of the butter in medium heavy noncorrosive saucepan over medium-high heat. Add tomato pulp, reserved tomato juice, and the time. Simmer, uncovered, stirring occasionally, until liquid is evaporated and tomatoes a reduced to thick purée, about 30 minutes. Remove thyme sprigs. Stir in salt and pepper; remove from heat. Whisk in remaining 3 tablespoons butter, 1 tablespoon at a time, whisking until each piece is incorporated before adding another.