In a small mixing bowl, combine the avocado with 3/4 of the lemon juice and a pinch of salt.
On a work surface, spread a large spoonful of hummus over half of a tortilla.
Spread a spoonful of the avocado mixture over the other half.
Place a handful of carrot sticks in the center, top with a sprinkle of radishes, and 1/4 cup of arugula leaves.
Fold in the top and bottom sides of the tortilla.
Fold in one of the sides length-wise and roll the tortilla, making sure the top and bottom stay tucked.
Repeat with the remaining tortillas.