Preheat broiler with rack about 6 inches from heat. Place chiles on a rimmed baking sheet; broil, turning occasionally, until evenly charred, 8 to 10 minutes. Transfer to a medium bowl and cover tightly with plastic wrap. Let stand for 10 minutes, then scrape off charred skin using a towel. Discard skin, stems, and seeds. Slice chiles into 1/4-inch-thick strips.
Meanwhile, heat oil in a large skillet over medium-high. Add zucchini; cook, stirring occasionally, until browned, about 3 minutes. Add chiles, garlic, salt, pepper, and 1/2 cup squash blossoms. Cook, stirring often, until garlic is fragrant and blossoms are wilted, about 45 seconds.
Divide tortillas between 2 rimmed baking sheets. Top each tortilla with 2 tablespoons cheese. Place 1 baking sheet in oven; broil until cheese is melted and tortilla is slightly charred, 1 to 2 minutes. Remove from oven and repeat with other baking sheet.
Divide zucchini mixture among tortillas. Top with remaining squash blossoms, sliced avocado, sour cream, pepitas, and cilantro. Serve with a squeeze of lime.
