2 serrano chiles, stemmed, seeded, and finely chopped
2-4 large ripe avocados, pitted, peeled, and roughly chopped
1/2 medium white onion, finely chopped
6 cups/1.4L chicken or vegetable stock
1 cup/250ml heavy cream
⅓ cup/78ml fresh lime juice
Kosher salt and freshly ground black pepper, to taste
2 plum tomatoes, cored, seeded, and finely chopped
Combine the serrano chiles, the avocados, and the onion in a food processor or blender, and process until a smooth paste forms. Add stock, cream, and lime juice, and purée until very smooth. Pour through a fine strainer into a bowl or pitcher, and season with salt and pepper; cover and refrigerate until chilled, at least 2 hours.
Garnish with tomatoes.