Combine 1 cup sugar, water and Lillet Rouge in a heavy bottomed saucepan. Heat on medium heat until just simmering. Add strawberries and rhubarb, stir to combine. Remove from heat and let it sit. Refrigerate and use within 7 days.
Melt butter and chocolate together in a microwave in 10 second intervals, stirring between each time. Once chocolate is just melted and smooth, let sit for a minute for it cool slightly. Mix in yolks one at a time, stirring until smooth. Set aside.
Beat egg whites on medium high in a stand mixer with a whisk attachment until foamy. Add the cream of tartar and beat until soft peaks start forming. Gradually add in the ¼ cup of sugar and beat until stiff peaks form.
Beat heavy cream with 2 tablespoons sugar, vanilla and instant espresso. Beat until medium peaks are formed. Fold egg mixture into the chocolate mixture making sure not to overmix. Then fold in the whipped cream, once again making sure not to overmix.