Prep the vegetables and beans so everything is ready to move quickly at the stove: peel and dice the sweet potato into uniform 1/2-inch cubes (this ensures even cooking), dice the red bell pepper, thinly slice the red onion, chop the cilantro, slice the avocado and cut the limes into wedges. Drain and pat the cooked black beans dry with paper towels — removing surface moisture helps them warm through without becoming mushy.

Par-cook (or roast) the sweet potatoes: for best texture, toss the diced sweet potato with 1 tablespoon olive oil and a pinch of salt, then spread on a rimmed baking sheet in a single layer. Roast at 220°C/425°F for 12–15 minutes until edges begin to brown and interior is tender. Roasting develops caramelized sugars and concentrates flavor. (Shortcut: you can also par-cook the cubes in a covered skillet with 1 tablespoon oil over medium for 8–10 minutes until nearly tender, then uncover and increase heat to brown.)

Heat a large, heavy skillet (cast iron or stainless steel) over medium-high heat and add 2 tablespoons olive oil. A hot pan gives the onions and peppers quick color without stewing. When the oil shimmers, add the sliced red onion and cook, stirring occasionally, 3–4 minutes until it softens and begins to pick up color — this builds savory, sweet flavor through caramelization.

Add the diced red bell pepper to the pan and cook 3–4 minutes more until the pepper softens and has a few charred spots. If using the optional minced garlic, add it with the pepper for the last 30–45 seconds — garlic burns quickly, so add late to preserve its flavor.

Add the par-roasted sweet potato cubes to the pan and spread them in an even layer. Let them sit undisturbed 2–3 minutes so the exposed faces brown and crisp — searing creates Maillard flavors and texture contrast. Then gently toss or flip to brown another side and cook 2 more minutes.

Lower the heat to medium and push the vegetables to one side of the pan. Add the drained black beans to the cleared side with 1 tablespoon olive oil, the ground cumin and smoked paprika. Toast the spices in the oil for 20–30 seconds to bloom them — this releases their essential oils and makes the spice flavors brighter. Stir the beans and spices together, then combine with the vegetables. Cook everything together 2–3 minutes so the beans heat through and pick up flavor; avoid prolonged stirring to prevent the beans from breaking down too much.

Taste and season with salt and freshly ground black pepper; add a squeeze of lime juice (start with half a lime) to lift the flavors and balance the sweetness of the potato. Lime brightens and contrasts the smoky paprika. If the hash looks dry, add a splash of water or another 1/2 tablespoon of oil and gently mix.

Assemble: divide the hash among four plates or shallow bowls. Arrange avocado slices on top, scatter chopped cilantro and add a lime wedge to each serving. Finish with a dollop (1 tablespoon) of plain yogurt or a few drops of hot sauce if using, and a pinch of flaky sea salt for contrast — the creamy cool yogurt or spicy hot sauce adds another layer of flavor and temperature contrast.

Serve immediately while the sweet potatoes have crisp edges and the beans are warm. Encourage diners to squeeze their lime and toss the avocado through the hash for a silky finish.