In a large saucepan, bring half and half to a simmer. Stir in Thai tea, turn off heat, and steep for five minutes.
In a bowl, whisk egg yolks and sugar together until yolks pale in color and thicken. Slowly ladle about one cup dairy mixture into yolks, whisking constantly, then transfer yolks to saucepan, whisking well to combine.
Turn heat on medium low and whisk frequently until a thin, syrupy custard forms. Add salt to taste, between ½ and 1 teaspoon. Custard should lightly coat back of a spoon and a swiped finger should leave a clean line. Do not cook custard until thick.
Pour through a fine mesh strainer and chill overnight before churning according to manufacturer's instructions. Chill ice cream in freezer for at least three hours before serving, with a drizzle of condensed milk on top. Ice cream is best eaten the day it is made.