Shad-Roe Sauce

A short French-style compound sauce: poached shad roe folded into espagnole. The original assumes you know how much brown sauce to make and how gently roe must be treated.

• Keep the water below a simmerThe membrane around each lobe contracts in boiling water and the roe bursts, scattering eggs and turning the lobe mealy. Bring the salted, acidulated water to a bare shiver, slip the roe in, and hold it there.
• What one shad roe isA "roe" is a joined pair of lobes, and sizes vary a good deal from fish to fish. Twenty minutes suits an average pair; a larger one may need longer, and it is done when the centre is opaque and firm to a skewer.
• Peel the membraneAfter cooling, slit and strip the connective membrane and the visible vein before you crumble, or the sauce carries tough threads. "Crumb up" means break the cooked eggs into loose grains, not a paste.
• Brown sauceThis means a stock-based brown sauce of the period -- espagnole or demi-glace, or the simpler browned-flour-and-stock sauce many books of the day meant by the term -- not modern gravy from a packet. Figure 1 to 1 1/2 cups of finished brown sauce for one roe; the original gives no quantity, so judge it by how thickly you want the eggs suspended.
• Add the roe off the heatFolded into simmering sauce, the grains stiffen and dry out. Take the pan off the burner, stir in the roe and the lemon juice, and warm it through only.
• Season lastThe poaching water was salted and the brown sauce is already reduced. Taste after the roe goes in, and expect to need pepper more than salt.
• Yield and servingRoughly a cup and a half of sauce, depending on how much brown sauce you make. It suits poached or broiled shad, and works the same way over sole, halibut or a plain white fish.