Skin and roughly cut up the watermelon and place on/in a plate/bowl. Using a peeler peel the carrots and place with the watermelon, half the the cucumber (peel it if you do not like the skin) and cut into slices.
Mix the watermelon,carrots, cucumber, seeds and lettuce leaves together. In a small bowl mis the lime and honey together and pour over the salad and give a good mix, sprinkle over the sprouts if using and serve.