Dice onion and red pepper. (Try to make dice match the cucumber dice.)
Allow vegetables to drain in a colander about 1 hour.
While vegetables are draining prepare your canner by filling it with enough water to cover your canning jars by 2 inches and bring water to a boil.
Preheat oven to 275°. Place canning jars on a baking sheet (preferably lined with silicone) and bake 20 minutes to sterilize the jars.
Prepare a bowl or saucepan with boiling water so you will be able to immerse the lids and bands in boiling water for 5 minutes just before you will seal the filled jars.
Press as much liquid out of the vegetables as possible and transfer to a large pot.
Add vinegar, mustard, salt, mustard seed, turmeric to the pot and mix well. Add the pectin and stir to mix.
Bring mixture to a boil, add the sugar and return to a boil, stirring frequently.
Ladle hot mixture into sterilized jars leaving ½" head space. Stir with a knife to remove any air bubbles. Wipe jar rims and seal.
Can closed jars for 10 minutes, with water covering jars by 2 inches.
Remove jars from canner and allow to cool at room temperature about 12 hours. Unscrew the band and check that the lid has sealed.
Store at room temperature in a dark place up to 1 year.