Add the red onion to a small bowl with the vinegar, water, salt, and sugar. Toss well and set aside to pickle.

Rinse the rice under cold water until the water runs mostly clear, then drain well.

Heat the olive oil in a small saucepan over medium heat. Add the sofrito and cook for 2 to 3 minutes until fragrant.

Add the garlic and cook for about 30 seconds. Stir in the sazón and oregano, then add the rice and toss until evenly coated.

Add the chicken broth and season lightly with salt. Bring to a boil, cover, reduce the heat to low, and cook for about 15 to 18 minutes, until the liquid is absorbed and the rice is fluffy and tender. Remove from the heat and let sit covered for 5 minutes before fluffing.

While the rice cooks, pat the shrimp dry and toss with the olive oil, garlic, adobo, oregano, and lime zest. Let sit for about 10 minutes.

Heat a large skillet over medium-high heat. Cook the shrimp in a single layer for 1 to 2 minutes per side, until golden and just cooked through.

During the final 30 seconds, add the butter and lime juice and toss to coat. Transfer the shrimp to a plate.

Return the skillet to medium-high heat. Add the butter, pineapple, and a pinch of salt. Cook for 4 to 5 minutes, letting the pineapple sit undisturbed for stretches so it caramelizes around the edges.

Drain the pickled onions and slice the avocado.

Pack the rice into a small cup or ramekin, gently press it down, then invert it onto each plate.

Arrange the shrimp, pineapple, avocado, and pickled onions around the rice. Finish with chopped parsley and lime wedges.