Step 1
Cut 1 lime in half; squeeze juice into a blender. Add 2 medium jalapeños, stems removed, 5 garlic cloves, 2 cups (packed) cilantro leaves with tender stems, ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt, and ½ cup water and blend until smooth. Transfer 2 Tbsp. cilantro purée to a small bowl; set aside.
Step 2
Place 3 Tbsp. cilantro purée in a medium bowl; finely grate in zest of 1 lime. Cut lime in half; squeeze in juice. Mix in ½ cup sour cream, 2 Tbsp. mayonnaise, and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt. Cover herb sauce and chill until ready to serve.
Step 3
Place 1½ cups jasmine or other long-grain rice in a medium bowl. Pour in cold water to cover and swish vigorously with your hands; drain. Repeat process until water runs clear (3–5 more times).
Step 4
Heat 2 Tbsp. vegetable oil in a large Dutch oven or other heavy pot over medium-high. Add rice and ½ tsp. ground cumin and cook, stirring, until rice is coated in oil, about 30 seconds. Add 1½ tsp. Diamond Crystal or ¾ tsp. Morton kosher salt, remaining cilantro purée in blender, and 2¼ cups water; stir to combine. Bring to a boil. As soon as bubbles appear along sides, reduce heat to low and cover; cook 15 minutes. Remove pot from heat; let rice sit (still covered) 15 minutes.
Step 5
Meanwhile, heat 2 Tbsp. vegetable oil in a large skillet over medium-high. Add ¾ lb. mixed mushrooms (such as oyster, shiitake, maitake, and/or crimini), torn into various sizes, and spread out in a single layer. Cook until golden, about 3 minutes per side. Transfer to a medium bowl. Add 1 Tbsp. vegetable oil to pan and cook remaining ¾ lb. mixed mushrooms until nearly golden, about 3 minutes per side.
Step 6
Return all mushrooms to pan; reduce heat to low. Scoot mushrooms to one side and add remaining 1 Tbsp. vegetable oil, then 1 tsp. paprika, remaining 1 tsp. ground cumin, and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt to empty side of skillet; season with freshly ground pepper. Give spices a quick stir to combine, then toss mushrooms to coat in spiced oil. Remove from heat.
Step 7
Cut remaining 1 lime into wedges. Gently mix reserved 2 Tbsp. cilantro purée into rice with a fork; fluff rice. Transfer to a platter and top with mushrooms. Drizzle some reserved herb sauce over (if it has thickened, stir in 1 Tbsp. cold water to loosen) and top with cilantro leaves with tender stems. Serve with lime wedges and remaining sauce.
