beef round (about 1 kg) • onion + 1/4 onion • garlic, or 3 if small + 2 or 3 more • Roma tomatoes • Oregano, to taste • Salt, to taste • water (2.5 liters) • carrots, grated • sliced lettuce • cucumber, sliced or cut into half-moons, seeds removed • Avocado, to taste • Pickled red or white onion, to taste