Pour 2 1/2 cups of water into a pot and turn on the stove. Leave the water to boil (about 5 minutes) or until bubbling. Take the frozen tortellini out of the freezer, and pour into boiling water. Let simmer for 15 minutes. While the tortellini is cooking, wash off cucumber and strip the skin off of it. Dice cucumbers and place into a large bowl.
Stir tortellini until soft. Shut off stove and drain the tortellini. Quickly pour into large bowl and mix with cucumbers.
Measure out 1/4 cup of Italian dressing and pour onto cucumbers and tortellini. Mix and toss until the dressing is throughout the whole dish. Cover and chill in refrigerator until ready to serve.