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1
Place the pancetta in a large pot over medium heat and fry it for about 10 minutes, until it is golden brown and slightly crispy.
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2
Add the onions and the olive oil and cook for 10 more minutes, until the onion is soft and light golden.
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3
Add the celery, drained beans, and 3 quarts of cool water.
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4
Bring the water to a boil.
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5
Take the pot off the heat to stir in the baking soda.
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6
Season the soup with salt and pepper and the hot pepper.
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7
Be careful not to add too much salt at this point; the water will reduce as you cook the beans and the soup will get saltier as it does.
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8
Return the soup to medium-low heat and simmer, uncovered, until the beans are tender, about 2 hours, stirring occasionally.
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9
Stir in the tomato paste and sugar and simmer the soup for about 10 minutes.
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10
Depending on how much water is left and how thick you like your soup, you may need to add some boiling water to the soup.
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11
Note that the starch from the pasta will thicken the soup even more.
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12
Bring the soup to a boil over medium-high heat.
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13
Stir in the ditalini and boil the pasta in the soup, stirring very often, until the pasta is tender, about 15 minutes.
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14
Serve hot, with grated Parmesan cheese.
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15
If you have leftovers, add some boiling water and heat the soup over low heat.
