Rinse the sugar snap peas under cold water, removing any dirt or debris, then trim the ends to prepare them for pickling.

Pack the cleaned sugar snap peas tightly into clean canning jars, leaving about a half inch of space at the top.

In a saucepan, combine vinegar, water, and sea salt; heat gently while stirring until the salt dissolves. Let the mixture cool completely before using.

Sprinkle the dill seed, crushed red pepper, and mustard seed evenly over the packed peas in the jars.

Carefully pour the cooled brine over the peas, leaving another half inch of space at the top.

Secure tightly with screw-type lids or canning lids with rings.

Place the jars in the fridge and let them sit for at least 24 hours before sampling.