Preparation

• For rhubarb mousse:
  Soften gelatin in water. Set aside for 5 minutes.
  Heat over low heat to dissolve.
  In a mixing bowl, combine the gelatin with the rhubarb puree.
  Fold in the whipped cream.
  
  For lemon mousse:
  
  Soften gelatin in water. Set aside for 5 minutes. Heat over low heat to dissolve. In a mixing bowl, combine the lemon rind, juice and sugar. Stir until sugar is dissolved. Add gelatin. Cool mixture but do not set.
  Beat the cream with the sugar until stiff. Fold into the lemon mixture.
  Beat egg whites and cream of tartar to a stiff peak. Fold into the lemon mousse.
  
  For the rhubarb purée:
  
  In a heavy medium saucepan, combine rhubarb and sugar. Cover mixture and let stand for 2 hours or more.
  Cook rhubarb over low heat for about 30 minutes. Stir in strawberries.
  Cool completely. Cover puree and chill until ready to serve.
  
  To assemble:
  alternate layers of rhubarb and lemon mousse in parfait glasses, wine glasses, or glass serving bowl. Refrigerate before serving.