Although red currants are classic in summer pudding, other combinations of berries, such as raspberries and blackberries or blueberries, can be used. Just be sure that at least half of the berries are red for the pudding to have the nicest color.
Combine currants, loganberries, sugar and water in a large heavy saucepan. Bring to a simmer, stirring, and simmer over medium-low heat for 2 minutes. Remove from the heat, stir in jam, liquor and lemon juice. Let cool completely.
Line a 1-quart pudding basin or souffle dish with plastic wrap, leaving a 4-inch overhang all around. Cut the bread slices in half diagonally, then fit them in the bottom and sides of the bowl, trimming further to fit snugly if needed. (You will have extra slices to be used for the top.)
Spoon the berry mixture into the bread-lined bowl; trim bread slices level with the top. Use remaining bread slices to cover the top. Fold the plastic wrap over the top of the pudding, then top with a plate slightly smaller than the diameter of the bowl. Weight the plate with a heavy can. Refrigerate at least 8 hours.
To serve, remove weight and plate, then fold back the overlap of plastic wrap. Set a rimmed serving plate over the bowl, then invert the pudding onto the plate. Remove the bowl and plastic wrap. Carefully cut wedges with a serrated knife and serve each portion with a dollop of yogurt.
Make Ahead Tip: Prepare through Step 3 up to 1 day in advance.
4 other carbohydrate, 1/2 fat-free milk