Step 1

Melt butter in medium saucepan on low heat

Step 2

Whisk in cornstarch until there are no lumps; turn the heat up a little, continue whisking 3 more minutes, until the mixture begins to combine; remove from heat

Step 3

Allow to cool for 2-3 minutes while continuously whisking

Step 4

Add lemon juice in 1 teaspoon increments, whisking constantly; salt to taste; strain through a fine meshed strainer and serve