Potato, Asparagus & Fennel Ragoût

• 2 Tbs. extra-virgin olive oil
• 1 small onion, sliced into wedges about 1/2-inch thick at the widest point
• Kosher salt and freshly ground black-pepper 
• 1 lb. thick asparagus, bottoms trimmed, spears cut into 2-inch pieces
• 1 large bulb fresh fennel (about 1 lb.), fibrous outer layer removed, cored, and cut into 1/4-inch dice
• 10 oz. red-skinned potatoes (about 2 medium), scrubbed and cut into 1/2-inch chunks
• 2 cups homemade or low-salt canned chicken broth
• 1 Tbs. heavy cream
• 2 tsp. Dijon mustard 
• 2 Tbs. chopped fresh dill or flat-leaf parsley
• 1/2 lemon

Heat the oil over medium-high heat in a large saucepan or a small Dutch oven. Add the onion, along with a few pinches of salt and a few grinds of pepper. Cook, stirring frequently, until the onion softens and starts to turn golden, about 5 min. Add the asparagus, fennel, and potatoes to the pot, along with a few more pinches of salt and pepper. Cook, stirring, until the vegetables are well coated with oil and the asparagus has turned bright green, 2 to 3 min. Add the chicken broth, raise the heat to high, and cover the pot. When it comes to a boil, reduce the heat to medium and keep the broth at a lively simmer. Cook, covered, until the potatoes are tender, 7 to 10 min. Stir in the cream, mustard, dill or parsley, and a squeeze or two of lemon juice. Adjust the seasonings and serve.