Avocado-tequila soup in watermelon

1 lb avocados, chopped
2 tbsp roughly chopped cilantro leaves
6 cup chicken stock, preferably homemade, chilled
1 serrano pepper
1 cup freshly squeezed orange juice, from 2 oranges
1/4 cup Tequila, preferably aged
Salt, to taste
1/2 tsp grated orange zest
1 watermelon

In a blender, combine avocado, cilantro, 3/4 cup chicken stock, serrano or jalapeno pepper. Add orange juice, tequila, salt, zest, and remaining chicken stock. Blend until smooth, in two batches if necessary. Strain through a sieve.
Cut watermelon in half crosswise and hollow out, forming a tureen. Seed watermelon and cut into 1/2-inch cubes. Pour soup into watermelon and garnish with watermelon cubes, reserving remaining watermelon for another use.