Seed peppers and grind them coarsely. Put peppers in a large bowl. Add salt; cover and let stand overnight. Drain off about half of the liquid, pour the peppers into a heavy saucepan, and add the vinegar and sugar. Bring to a boil, reduce heat and simmer for about 1 hour, stirring occasionally. Remove from heat and add red food coloring a few drops at a time to make the jam a bright red. Cool slightly, stirring occasionally, and spoon into sterilized jars. Store in a cool, dark place.