1 (1/4-lb) piece double-smoked bacon*
3 1/2 tablespoons olive oil
3/4 lb fresh shiitake mushrooms, stems discarded and caps quartered
1 teaspoon kosher salt
1 1/2 tablespoons fresh lemon juice
1/2 tablespoon red-wine vinegar
1/2 tablespoon coarse-grain mustard
1/2 teaspoon black pepper
4 oz fresh pea shootspea shoots (4 cups)
4 oz baby spinach leaves (4 cups)
1 bunch fresh chives, cut into 1-inch lengths
6 radishes, cut into matchsticks
*Available from specialty foods shops and by mail order from Citarella (212-874-0383).
Cut bacon into 3/4-inch-thick matchsticks and cook in a heavy skillet over moderately low heat, stirring, until crisp but still chewy, 6 to 8 minutes. Transfer with a slotted spoon to paper towels to drain.
Pour off fat from skillet and add 1 1/2 tablespoons oil, mushrooms, and 1/2 teaspoon salt. Cook over moderate heat, stirring occasionally, until mushrooms are golden, about 8 minutes, then cool.
Whisk together lemon juice, vinegar, mustard, remaining 1/2 teaspoon salt, pepper, and remaining 2 tablespoons oil in a large salad bowl until blended.
Add pea shoots and spinach to dressing and toss to coat. Add bacon, mushrooms, chives, and radishes and toss again.