Finely dice the yellow onion and red bell pepper, then mince the garlic. Drain and rinse the black beans in a fine-mesh strainer until the water runs mostly clear. Measure the remaining ingredients before heating the pot; preparing everything first prevents the garlic and ground spices from scorching while you assemble the chili.

Place a 5- to 6-quart (4.7- to 5.7-L) Dutch oven or heavy-bottomed pot over medium heat. Add 2 tablespoons (30 mL) olive oil and heat for about 1 minute, until the oil looks fluid and shimmers lightly. Avoid letting the oil smoke; moderate heat provides enough energy to soften the vegetables without burning them.

Add the diced yellow onion and red bell pepper to the hot oil. Cook over medium heat for 6 minutes, stirring occasionally, until the onion becomes translucent and the pepper begins to soften. Look for light golden edges and a gentle sizzle. This stage reduces raw vegetable moisture and builds the chili's savory foundation.

Stir in the minced garlic, 2 tablespoons (16 g) chili powder, 2 teaspoons (4 g) ground cumin, and 1 teaspoon (2 g) smoked paprika. Cook over medium-low heat for 1 minute, stirring continuously, until the garlic smells fragrant and the spices coat the vegetables evenly. Keep the mixture moving; ground spices release their aromas quickly and can become bitter if scorched.

Add 2 tablespoons (33 g) tomato paste and stir thoroughly. Cook over medium-low heat for 2 minutes, scraping the bottom of the pot, until the paste darkens slightly and begins coating the vegetables in a thick reddish layer. This brief concentration step removes some raw tomato sharpness and develops a deeper savory base.

Stir in the 15-ounce (425 g) can of pumpkin puree, 2 cans of drained and rinsed black beans (approximately 3 cups/510 g), the 14.5-ounce (411 g) can of diced tomatoes with their juices, and 1 1/2 cups (360 mL) vegetable broth. Add 1 teaspoon (6 g) fine sea salt and 1/4 teaspoon (0.5 g) black pepper. Stir until the pumpkin is fully incorporated and no dense patches remain. Increase the heat to medium-high and cook for approximately 5 minutes, stirring occasionally, until small bubbles begin breaking across the surface.

Reduce the heat to low or medium-low to maintain a gentle simmer. Cook uncovered for 20 minutes, stirring every few minutes and scraping the bottom of the pot to prevent sticking. The chili should gradually thicken, with small bubbles rising slowly through the sauce. It is ready when the beans are heated through, the vegetables are tender, and the sauce coats a spoon without running off immediately. Avoid a vigorous boil, which can cause the thick pumpkin mixture to splatter or scorch.

Remove the pot from the heat and stir in 1 tablespoon (15 mL) freshly squeezed lime juice. Mix until evenly distributed, then check that the chili has a thick but spoonable consistency. The lime juice adds acidity that sharpens the savory spices and balances the pumpkin's natural sweetness. Ladle the hot chili into serving bowls.