To recreate this fun and easy procedure at home all you need are:

A thick elastic band: found in the wild on grocery store broccoli
Scissors
A sewing needle
Fishing line: 8 lb test will do
(most if not all of these items can be found in the third drawer of any kitchen)

The procedure: (as may be performed by a right handed human)

Place the elastic on the thumb, then the forefinger of the left hand creating a loop.

Using the scissors, cut the elastic once so that is no longer a loop.

Fold the elastic in two and using the scissors, cut the elastic in half.

Now you should have two halves of elastic to work with.

Place both pieces of elastic on a clean, unencumbered, level work surface.

Using the fishing line, thread the sewing needle.

Place the threaded needle on the work surface.

Take the two pieces of elastic and place them back to back.

Align the tops of the elastics and pinch them between the thumb and forefinger of the left hand
leaving 80mm of elastic exposed above the thumb and forefinger.

Using your right hand pick up the threaded sewing needle.

Begin suturing the exposed elastic by piercing it on the left at the midpoint between your hand and the top of the elastics.

Push the threaded sewing needle through both pieces of elastic,
Then bring the threaded sewing needle back over the top of the elastic (towards yourself),
make a second puncture at the same level and 20mm to the right of the first.

Repeat this maneuver until you reach the rightmost extremity of the exposed elastic.

Once at the rightmost extremity, remove the sewing needle from the fishing line.

Place the sewing needle on the work surface.

Tie a secure knot in the fishing line as close to the elastic as possible,
using scissors, remove excess fishing line above the knot.

Go back to where you began the suture and tie an other secure knot.

Using scissors, remove excess fishing line above the knot.

Return the scissors, sewing needle and fishing line to the third drawer of any kitchen.

Congratulations, you have successfully repaired a severed Broccoli tendon!
To test the quality of your work, hold each end of the elastic and gently pull in opposite directions.