Ingredients

• 1/4 teaspoon fennel seeds
• 2 tablespoons olive oil
• 1/2 medium onion, finely chopped
• Kosher salt
• 2 chipotle chiles
• 1 large pasilla, New Mexico, or guajillo chile, seeds removed
• 3 garlic cloves, finely chopped
• 1/2 teaspoon ground coriander
• 1 (28-ounce) can whole peeled tomatoes
• 1 1/2 pounds russet potatoes, scrubbed, cut into 1-inch pieces
• Kosher salt
• 1 large egg yolk
• 1 garlic clove, finely grated
• 1 teaspoon red wine vinegar
• 3/4 cup grapeseed oil
• Vegetable oil (for frying; about 8 cups)
• 3/4 teaspoon paprika
• 1/4 teaspoon ground cumin
• A spice mill or mortar and pestle; a deep-fry thermometer

Instructions

1. Grind fennel seeds in spice mill or mortar and pestle; set aside. Heat oil in a large skillet over medium. Add onion, season with salt, and cook, stirring often, until golden and soft, 8–10 minutes. Add chiles, garlic, coriander, and reserved fennel and cook, stirring, 1 minute. Add tomatoes, crushing with your hands as you go, and juices; reduce heat and gently simmer, stirring occasionally at first and more frequently as sauce thickens, until sauce is thickened and jammy, 50–60 minutes. Let cool; discard chiles. Pulse sauce in a food processor to a coarse purée.
2. Make the potatoes and assemble: While tomato sauce is cooking, rinse potatoes in a colander under cold water until water runs clear. Transfer to a large pot and pour in cold water to cover by 1". Season with salt and bring to a gentle simmer; cook until potatoes are just tender, 20–25 minutes. Drain and transfer potatoes to a kitchen towel–lined rimmed baking sheet. Chill (uncovered) until cold, about 1 hour. Meanwhile, whisk egg yolk, garlic, and vinegar in a small bowl to combine. Whisking constantly, gradually drizzle in grapeseed oil and continue to whisk until aioli is thickened and emulsified. Season with salt; stir in 1 tsp. water. Fit a large pot with thermometer and pour in vegetable oil to measure 3". Heat over medium-high until thermometer registers 325°F. Working in batches, fry potatoes until skins begin to slightly bubble around edges but do not brown, about 2 minutes. Using a slotted spoon, transfer potatoes to paper towels to drain. Reheat oil until thermometer registers 375°F. Working in batches, refry potatoes until golden brown and very crisp, about 3 minutes per batch. Transfer to fresh paper towels to drain. Toss potatoes, paprika, and cumin in a large bowl; season with salt. Serve potatoes with tomato sauce and aioli.
3. While tomato sauce is cooking, rinse potatoes in a colander under cold water until water runs clear. Transfer to a large pot and pour in cold water to cover by 1". Season with salt and bring to a gentle simmer; cook until potatoes are just tender, 20–25 minutes. Drain and transfer potatoes to a kitchen towel–lined rimmed baking sheet. Chill (uncovered) until cold, about 1 hour.
4. Meanwhile, whisk egg yolk, garlic, and vinegar in a small bowl to combine. Whisking constantly, gradually drizzle in grapeseed oil and continue to whisk until aioli is thickened and emulsified. Season with salt; stir in 1 tsp. water.
5. Fit a large pot with thermometer and pour in vegetable oil to measure 3". Heat over medium-high until thermometer registers 325°F. Working in batches, fry potatoes until skins begin to slightly bubble around edges but do not brown, about 2 minutes. Using a slotted spoon, transfer potatoes to paper towels to drain.
6. Reheat oil until thermometer registers 375°F. Working in batches, refry potatoes until golden brown and very crisp, about 3 minutes per batch. Transfer to fresh paper towels to drain.
7. Toss potatoes, paprika, and cumin in a large bowl; season with salt. Serve potatoes with tomato sauce and aioli.
8. Do Ahead Tomato sauce can be made 4 days ahead; cover and chill. Bring to room temperature before serving. Potatoes can be blanched 1 day ahead. Let cool; cover and chill.
9. Tomato sauce can be made 4 days ahead; cover and chill. Bring to room temperature before serving.
10. Potatoes can be blanched 1 day ahead. Let cool; cover and chill.