Line an 8-inch square pan with parchment and lightly oil the paper and sides.
Simmer cranberries and water in a saucepan over medium heat until berries burst and soften, 8–10 minutes.
Blend the mixture until smooth, then press through a fine strainer to remove skins and seeds.
Measure about 2 cups of the strained cranberry puree; return it to the saucepan over medium heat.
Stir in corn syrup, lemon juice, orange zest, and salt; bring to a gentle simmer.
Whisk pectin with 1/2 cup of the sugar. Gradually sprinkle this into the hot puree, whisking constantly.
Boil for 1 minute, then add the remaining sugar. Cook, stirring often, until thick and glossy, 8–12 minutes.
Check for gel at 220°F or when a spoon trail holds for a few seconds. Remove from heat.
Pour into the prepared pan and smooth the top. Cool at room temperature until firm, 3–4 hours.
Lift out, cut into 1-inch squares, and toss in the coating sugar to finish.