Saute onions in olive oil, until translucent. To avoid browning, cover the saucepan. Add sweet peas, 1/2 tsp. salt and 1/4 tsp. black pepper. Simmer on low heat, partially covered, for approximately 40 minutes, stirring occasionally.

Cook pasta in salted (one good handful) boiling water for approx. 7 minutes (still firm and not quite cooked). Drain enough water so that the ditalini remains barely covered with liquid. (Note: it's very important to save some of the drained water. You may need to add it back to the pot if the pasta gets too dry, or if you'd like it a little "soupy")

Add the peas and simmer over low/medium heat until the pasta is cooked al dente. (usually 2 - 3 additional minutes)