Prepare 4 (1-cup) containers.
In a small bowl, add 1/4 cup cold milk. Sprinkle the gelatin over and whisk for 10 seconds. Set aside for 10 minutes to soften.
In a medium saucepan, combine 2 cups milk, heavy cream, sugar, milk powder and soften gelatin. Cook over medium-low heat until warm through, and everything has dissolved, whisking occasionally, about a few minutes. Do not bring to a simmer or boil.
Divide the mixture into the containers. Chill uncovered in the fridge until set, at least 4 hours. Cover with plastic wrap once cooled.
For the strawberry sauce, wash the strawberries, pat dry, hull and cut into 1/4-inch cubes.
In a small non-reactive saucepan, add strawberries, sugar, lemon zest & lemon juice. Bring to a boil over medium heat, then reduce heat to medium-low and cook for 15 minutes, stirring occasionally. Remove from heat and set aside to cool for 10 minutes.
Carefully transfer the sauce to clean heat-proof containers or glass jars (with lid). Cool to room temperature. Cover with lid and store in the fridge.
To serve, add a heaping tablespoon of strawberry sauce on top of each cup of pudding. Serve cold. Add more sauce if needed.