Preparation Bring plums and 3/4 cup water to a boil in a small saucepan. Reduce heat to medium-high and simmer, stirring occasionally and mashing plums with the back of a spoon, until plums have completely broken down, about 15 minutes. Pour plum mixture through a fine-mesh sieve set over a small bowl, pressing on solids to extract as much purée as possible; discard solids in sieve. Let purée cool. Add oil, vinegar, and 2 tablespoons water to purée; whisk to blend. Season dressing to taste with salt and pepper. DO AHEAD: Dressing can be made 1 week ahead. Cover and chill. Divide greens among plates. Scatter nectarines, cheese, and almonds over, dividing equally, and drizzle some of dressing over. Season with salt and pepper.
Preparation Bring plums and 3/4 cup water to a boil in a small saucepan. Reduce heat to medium-high and simmer, stirring occasionally and mashing plums with the back of a spoon, until plums have completely broken down, about 15 minutes. Pour plum mixture through a fine-mesh sieve set over a small bowl, pressing on solids to extract as much purée as possible; discard solids in sieve. Let purée cool. Add oil, vinegar, and 2 tablespoons water to purée; whisk to blend. Season dressing to taste with salt and pepper. DO AHEAD: Dressing can be made 1 week ahead. Cover and chill. Divide greens among plates. Scatter nectarines, cheese, and almonds over, dividing equally, and drizzle some of dressing over. Season with salt and pepper.