Bring water to a boil. In a blender or food processor, combine cashews, agar and salt. Process to fine crumbs. Pour in (1/2 cup of the boiling water and process mixture for about 1 minute. With machine running, gradually add remaining boiling water, then process on high for 2 more minutes. Add vanilla, sugar, tofu and process 1 more minute.
Transfer mixture to saucepan and heat over low heat, stirring constantly until air bubbles have subsided, 10 to 15 minutes. Do not let mixture boil. Distribute mixture evenly between 4, 6 oz ramekins. Cover with foil and let cool to room temperature. Refrigerate until thoroughly chilled.
Before serving, blot moisture from tops of custards using a paper towel. Sprinkle each dessert with 7mL (1 1/2 tsp) brown sugar. Place cups under broiler for about 1 minute, until sugar is bubbly. Return to room temperature before serving.
Nutrition per serving: 212 calories, 10 g fat; 5.5 g protein; 50 g carbohydrate; 144 mg sodium.