Cucumber Ketchup - cooking recipe

Ingredients

3 very large cucumbers - peeled, seeded, and chopped
2 large onions, chopped
1/2 cup salt
1 cup apple cider vinegar
1/4 cup mustard seed
1 teaspoon ground black pepper

Preparation

Mix cucumbers and onions in a large bowl; stir in salt until thoroughly combined. Transfer mixture to a colander, cover colander with plastic wrap, and let drain overnight.
Place drained vegetables into a large bowl and pour in apple cider vinegar; stir to combine. Working in batches if necessary, place vegetables with vinegar into a blender and puree. Pour puree into a bowl and season with mustard seed and black pepper. Spoon the ketchup into small jars with lids; cover and store in refrigerator for 3 days before serving. Ketchup keeps well in the refrigerator.