Sopa azteca / sopa de tortilla (tortilla soup)

Ingredients

• For the broth
• 600 g tomatoes, charred whole under a dry broiler or directly over flame until blackened in patches
• 3 pasilla negro chiles, stems and seeds removed; do not substitute ancho or mulato
• 3 garlic cloves, charred with the tomatoes
• ½ white onion, charred with the tomatoes
• 1.2 litres chicken stock, good, unsalted
• 30 ml neutral oil, for frying the blended base
• For the tortilla strips
• 8 day-old corn tortillas, cut into 5 mm strips
• 500 ml neutral oil, for deep-frying at 175 °C
• For the garnish
• 200 g panela or requesón cheese, cut into 1 cm cubes
• 2 avocados, ripe; peeled, stoned, and sliced or cubed at service
• 120 ml crema, Mexican-style; or crème fraîche as a close substitute
• 2 chipotle chiles in adobo, whole or blended into the crema
• 1 sprig epazote, fresh; leaves picked

Method

1. 1
   Char the tomatoes, garlic, and onion under a dry broiler or directly over a gas flame, turning until the skins are blackened in patches and the flesh is softened. Separately, toast the pasilla negro chiles briefly in a dry pan — 20 to 30 seconds per side — until fragrant and pliable, then soak in just-boiled water for 15 minutes. The chiles are ready when they have turned supple and smell of dark fruit and earth.
2. 2
   Drain the soaked chiles. Blend the charred tomatoes, onion, garlic, and drained pasilla negro chiles together until smooth. Pass the blended mixture through a medium-mesh sieve, pressing firmly with a ladle to extract all liquid; discard the solids. The strained base should be a deep, even burgundy-red with no visible fibres.
3. 3
   Heat 30 ml of oil in a heavy pot over high heat until shimmering. Pour in the strained base all at once — it will spatter — and fry, stirring constantly, for 4 to 5 minutes. This is where the dish lives or dies: the base must fry hard in the hot oil until it darkens by several shades, thickens perceptibly, and the raw smell fully gives way to a deep, roasted aroma. An insufficiently fried base will taste flat and tinny no matter what follows.
4. 4
   Pour in the chicken stock, stir to combine, and bring to a steady simmer. Cook for 15 to 20 minutes over medium heat. Season with salt. The finished broth should coat a spoon lightly and carry a clean, smoky depth; taste and adjust salt before proceeding.
5. 5
   Heat 500 ml of neutral oil in a deep, heavy pan to 175 °C. Fry the 5 mm tortilla strips in small batches, turning once, until golden and rigid. Lift out with a slotted spoon and drain on a rack or absorbent paper. The strips are ready when they hold their shape without flexing and are uniformly pale gold; they will continue to crisp as they cool.
6. 6
   Warm the serving bowls. Arrange in each bowl a portion of cheese cubes, avocado, a few epazote leaves, a chipotle chile (or a spoonful of crema blended with chipotle), and a handful of crispy tortilla strips. Add the crema. Do not assemble the bowls more than two or three minutes before service — the tortilla strips begin to soften immediately on contact with moisture.
7. 7
   Bring the broth back to a full simmer. At the table or immediately before service, ladle the hot broth over the garnished bowls. The soup is correctly served when steam rises from the bowls and the tortilla strips are still audibly crisp when touched with a spoon.