Wash and dry produce.

Halve lime. Trim and halve cucumber lengthwise; thinly slice crosswise into half-moons. Finely chop cilantro.

In a small bowl, combine half the vinegar (you’ll use the rest later), juice from half the lime, ½ tsp sugar (1 tsp for 4 servings), and a pinch of salt.

Stir in cucumber. Set aside to quick-pickle.

Heat a drizzle of oil in a large, preferably nonstick, pan over medium-high heat. Add carrots and cook, stirring, until just tender, 1 minute. Season with salt and pepper.

Turn off heat; transfer to a plate.

Heat another drizzle of oil in same pan over medium-high heat. Add beef*; season with a pinch of salt and pepper. Cook, breaking up meat into pieces, until browned and cooked through, 4-6 minutes.

Stir in sweet soy glaze and remaining vinegar. Bring to a simmer, then immediately turn off heat. Taste and season with salt and pepper.

In a second small bowl, combine mayonnaise with Sriracha to taste. Season with salt. Stir in water 1 tsp at a time until mixture reaches a drizzling consistency.

Wrap tortillas in damp paper towels and microwave until warm and pliable, 30 seconds.

Divide tortillas between plates and fill with saucy beef, carrots, pickled cucumber (draining first), and cilantro. Drizzle with Sriracha mayo. Cut remaining lime into wedges and serve on the side.