Beef

Rinse rice in a fine-mesh sieve until water runs clear, then cook with water and a pinch of salt until tender; keep covered off heat.
Peel and finely chop garlic; zest and quarter lime; trim and halve cucumber and slice into half-moons; halve, peel, and medium-dice onion; trim, peel, and grate carrot.
Combine sliced cucumber and juice from half the lime with sugar and a pinch of salt to quick-pickle.
Mix mayonnaise with a pinch of chopped garlic, a squeeze of lime juice, and sriracha; season to taste.
Heat a drizzle of oil in a large pan over medium-high, then cook the diced onion until softened.
Add ground beef and the remaining garlic, break up and cook until browned, then stir in soy sauce and turn off the heat; season to taste.
Fluff the cooked rice with a fork and stir in lime zest and butter.
Divide rice between bowls and top with the cooked beef, grated carrot, and the pickled cucumber.
Finish each bowl with a squeeze of lime juice and a drizzle of the sriracha mayo.