In a medium saucepan, heat the half and half with the vanilla bean and scrapings until steaming and small bubbles appear around the sides of the pan. Cover and steep for 30-60 minutes.
Pour the heavy cream into a quart-sized heat-proof container, such as a mason jar, and set aside. If you have an instant-read thermometer, have it handy.
Place the egg yolks in a medium bowl set on a damp towel to stabilize it. Add the sugar and salt, whisking to combine. Reheat the half and half to a bare scald. Whisking constantly with one hand, pour the hot dairy very slowly into the yolks. (This is called tempering and prevents the yolks from scrambling.)
Pour the mixture back into the saucepan and set over a medium-low flame. Cook, stirring constantly with a heat-proof silicone spatula, scraping the sides and bottom of the pot, until the custard just begins to 'stick' (or form a thickened film) on the bottom of the pot (you may have to tilt the pan to see it), or registers 170º on an instant-read thermometer, 5-10 minutes.
Immediately pour the custard into the container of cold cream, stir to combine, and chill in the fridge for at least 4 hours,preferably overnight.
Place the ice cream base in the freezer for 30 minutes to get it really cold. Strain the mixture through a fine mesh sieve, then process in an ice cream maker according to the manufacturer instructions. 'Cure' in the freezer for at least 2 hours for a firmer consistency.