Prepare the poaching syrup: In a medium saucepan, combine the water, 1/2 cup sugar, and lemon zest strips. Bring to a simmer over medium heat, stirring until the sugar is completely dissolved. Reduce heat to low.

Gently place the peach halves cut-side down into the simmering syrup. Poach for 10-15 minutes, or until the peaches are tender when pierced with a fork. Remove from heat, stir in the vanilla extract, and allow the peaches to cool completely in the syrup.

Prepare the raspberry sauce: In a small saucepan, combine the raspberries, 1/4 cup sugar, and lemon juice. Cook over medium heat, stirring occasionally, for about 5-7 minutes until the berries break down and the sauce thickens slightly.

Strain the raspberry sauce through a fine-mesh sieve into a clean bowl to remove the seeds. Press down on the solids to extract all the liquid. Chill the sauce until ready to serve.

To assemble the Peach Melba, place two warm or chilled peach halves in each serving dish or bowl. Top each serving with 2-3 scoops of vanilla ice cream.

Spoon a generous amount of the chilled raspberry sauce over the ice cream and peaches. Garnish with toasted sliced almonds and serve immediately.