Beet juice gives this springy dessert a super-vibrant hue, but it’s the strawberry flavor that shines. Look for beet juice in the bottled juice section at the supermarket.
Process beet juice and hulled whole strawberries in a blender until very smooth, about 1 minute. Pour into a saucepan. Stir in milk, honey, vanilla, and salt. Cook over medium, stirring occasionally, until 140°F on a candy thermometer, 5 to 6 minutes.
Meanwhile, stir together hot water and gelatin in a small bowl; let stand 3 to 4 minutes.
Stir gelatin mixture into strawberry mixture in saucepan. Pour evenly into 8 (4-oz.) ramekins. Cover loosely with parchment paper or plastic wrap, and refrigerate until set, 4 hours or up to overnight.
To serve, uncover ramekins, and top each with strawberry slices; sprinkle evenly with pistachios.