In a heavy medium saucepan, toast almonds, rice, and cinnamon on high heat, tossing frequently, until almonds begin to smell aromatic, 2 to 3 minutes. Add half and half, stir to combine, and bring to a bare simmer. Remove from heat, cover, and let steep for two hours.

In a second saucepan, whisk together sugar and egg yolks until well combined and slightly thickened.

Using a fine mesh strainer or a couple layers of cheesecloth, strain dairy mixture into a large measuring cup or bowl. Press down firmly on rice with a wooden spoon to release as much dairy and rice starch as possible. Strained dairy should yield about 2 ½ cups. Discard rice and almonds.

Transfer strained dairy to saucepan with egg yolks and sugar and whisk until very well combined. Put saucepan on medium heat and cook, stirring frequently, until a custard forms on the back of a spoon and a swiped finger leaves a clean line. Stir in vanilla, then salt to taste.

Pour custard through a fine mesh strainer into an airtight container and chill overnight. The next day, churn according to manufacturer's instructions. Transfer ice cream to container and chill in freezer for at least 3 to 4 hours before serving.